Based on the perspective of optimal financial structure, this paper empirically analyzes the nonlinear relationship between financial structure and economic growth by using the provincial panel data from 2001—2015 in China. The results show that there exist differences of financial structural effect to promote economic growth in different regions. Only when the regional development level reaches the threshold value can the financial structural market-orientation significantly promote economic growth. Furthermore, the higher the economic development level and marketization level and the more mature the legal environment is, and the more significant the financial structural economic growth effect is And a moderate financial development level can significantly promote the financial structural economic growth effect, when the financial development level is too high, the financial structural market-orientation can no longer significantly promote the economic growth.