Abstract：As a key component of a unified national market, financial integration is vital for improving the adaptation of finance to economic development in the new era. This paper calculates financial cross-domain support networks to reflect the distribution and evolution of financial integration among various provinces. It explores the nonlinear influence characteristics of financial integration on the high-quality coordinated development of regional economy and clarifies the influence mechanism between them.The results show that, firstly, the degree of financial integration has gradually increased, with some less-developed provinces witnessing an increase in their embeddedness in the financial cross-domain support relationship network. Secondly, financial integration has an inverted “U-shaped” influence on high-quality coordinated development of regional economy.When the financial cross-domain support relationship is at a relatively low level, it mainly reduces the difference of regional economic high-quality development by promoting the high-quality economic development of the less-developed regions. With the gradual increase of the value of the financial cross-domain support relationship, its promoting effect on the high-quality economic development of the less-developed regions shows a marginal decreasing trend. When the financial cross-domain support relationship is at a relatively high level, it has a relatively greater inhibitory effect on the high-quality economic development of less-developed provinces, and a relatively greater promotion effect on the high-quality economic development of relatively developed provinces, thus leading to the widening of the development gap between different regions.This paper gives three suggestions. Firstly, improve the balance of financial resources in spatial allocation. Secondly, enhance the strength of financial cross-domain support relationship. Thirdly, utilize comprehensive transportation channels and strengthen inter-regional factor flow and industrial cooperation to give play to the driving effect on the surrounding underdeveloped regions.

Keyword：Financial Integration; High-Quality Economic Development; Regional Coordinated Development; Financial Cross-Domain Support Network;