Abstract: Innovation is the primary driving force behind development． In the current period, China's scientific and technological innovation has become the focus of world attention． Faced with the squeeze and competition from the " First Group" countries such as the United States, Japan and European countries, the construction of an innovative country has entered a decisive stage．As a basic guarantee for the continuous development of innovation activities, R＆D investment is essential to promote corporate innovation．In 2017, the intensity of China's R＆D expenditure ( ratio to GDP) reached 2.15% , but there was still a gap compared with the level of 2.5% － 4% in major developed countries． In recent years, how to increase R＆D investment has attracted extensive attention from the academic community．

We focus on the impact of analysts as information intermediaries in the capital market on R＆D investment of enterprises．Although analysts can reduce the degree of information asymmetry between company and outside, they will also increase the pressure on short-term performance goals of company． According to the information interpretation mechanism, analysts rely on their professional information collection, processing, and analysis capabilities to communicate the intrinsic value of the company through profit forecasting and rating reports, reducing the information asymmetry between external investors and the company, and alleviating the company's financing constraints and entrusted agency issues, thereby increasing the company's R＆D investment and promoting corporate innovation; according to the performance pressure mechanism, the analyst's job content is to predict and evaluate the short-term performance of the company, which will cause performance pressure on managers, and due to concerns about their reputation, wealth, and career development, managers will reduce long-term innovation investment in order to pursue short － term performance goals, reduce corporate R＆D investment, and inhibit corporate innovation． Therefore, the existing literature on the impact of analysts on corporate R＆D innovation has not yet reached a consensus conclusion．In addition, existing studies have shown that analysts' predictions are generally biased by optimism, subject to conflicts of interest such as underwriting business, increasing commission income, and maintaining customer relationships．

Based on this, this paper studies the impact of analyst optimism bias on corporate R＆D investment, the role of conflicts of interest in it, and the role of corporate information transparency． Specifically, this paper selects A -share listed companies with R＆D expenditures in Shanghai and Shenzhen in 2007 -2017 as a sample to empirically test the relationship between analyst optimism bias and corporate R＆D investment, and further examine the impact of the " conflict of interest" of analysts and corporate information transparency on this relationship． The research results show that:(1) the analyst's optimistic bias is significantly negatively correlated with the company's R＆D investment, indicating that the analyst's optimistic bias will inhibit the company's R＆D investment;(2) the higher the institutional investor's shareholding ratio, the company's refinancing．The more significant the negative relationship between analyst optimism bias and corporate R＆D investment, indicating that the " conflict of interest" will aggravate this relationship;(3) the improvement of corporate information transparency can alleviate the negative effects of analyst optimism bias on corporate R＆D investment． This paper further adopts methods such as changing the measurement of analyst attention and analyst optimism bias, selecting a first-order difference model to eliminate possible endogenousness of the model, and defining refinancing behavior only as equity refinancing behavior and changing the measurement of information transparency as robustness tests, and the above robustness tests still support the conclusions of this paper．

From a theoretical point of view, this paper enriches and expands the research on the economic consequences of analysts ' optimistic bias and the factors of corporate R＆D investment; examines their impact on corporate R＆D investment from the perspective of analysts' optimistic bias, and identifies specific mechanisms and deepen the impact of analysts' research on corporate innovation activities; and aiming at the negative impact of analysts' optimistic bias on corporate R＆D investment, it further explores the role of " conflicts of interest" faced by analysts and the role of transparency of information．It adds new evidence to the study of analysts' " conflicts of interest" and corporate information transparency．Some studies have shown that in China's capital market, the information interpretation mechanism plays a leading role in analysts' attention to the impact on enterprise innovation．As a whole, analysts' attention can promote enterprise innovation．The research in this paper finds that analyst optimism bias will have a further effect on corporate innovation．Analyst optimism bias will strengthen the impact of performance pressure mechanism and weaken the effectiveness of the information interpretation mechanism, and generally have a negative impact on corporate R＆D investment．This paper expands the research scope of the impact of analysts on corporate innovation．The existing literature usually limits the research object to the number of analysts who track companies． This paper further tests the influence of optimistic bias in analysts' earnings forecast, and theoretically deepens the understanding of information interpretation mechanism and performance pressure mechanism． Most of the previous studies focused on the influencing factors of analysts' optimistic bias．In recent years, scholars began to pay attention to its economic consequences． There have been studies on the risk of stock price collapse, enterprise merger and acquisition, etc． In this paper, analysts' optimistic bias is further related to enterprise R＆D investment, thus enriching the research on the economic consequences of analysts' optimistic bias． In terms of application value, this paper suggests that the supervisory layer needs to further strengthen the isolator system, at the same time strengthen the education of analysts' professional ethics, improve the professionalism of analysts, ensure the independence and objectivity of analysts, and give full play to analysts as information intermediaries in capital market．In addition, enterprises should further improve the quality of information disclosure and information transparency, so that external investors can correctly judge and evaluate the intrinsic value of the enterprise, strengthen tolerance for innovation failure, and reduce short － term performance pressure on managers．

Because this study only focuses on the relationship between analyst optimism bias and R＆D investment, it has not yet penetrated into the specific performance of its performance － enhancing pressure mechanism, that is, the mechanism of its action has yet to be further tested．Therefore, follow-up research can be carried out from the perspective of the impact path of analysts' optimistic bias on corporate R＆D investment．

Key words: analyst optimism bias; R＆D investment; conflict of interest; transparency of information