Abstract: The continuous improvement of firm productivity can help enterprises to obtain excess profits in the fierce market competition，thereby creating higher value for shareholders． Based on the data of China's listed companies during the years from 2007 to 2018，the effect of controlling shareholder's shareholding ratio on firm productivity was studied．The research results show that the increase in the shareholding ratio of the controlling shareholder promotes the improvement of firm productivity．Further research on the mechanism of action has found that among companies with fewer analysts tracking，lower product market competition，and audits conducted by small firms，the controlling shareholder's shareholding ratio has a more significant role in promoting firm productivity，indicating that the controlling shareholder's shareholding can promote firm productivity through the monitoring effect．Regulatory departments should be fully aware of the important role played by the shareholding structure in the process of firm productivity，and further strengthen the protection for investors．Also,the listed companies should pay more attention to improving the level of governance，continuously optimizing the equity structure and improving firm productivity．