Based on the dynamic panel data of 30 provinces in China from 2001 to 2016, the deepening level of financial capital is measured from the scale and structure of capital supply. The quality of economic development is measured by using the five dimensions of effectiveness, stability, coordination, sustainability and sharing of economic growth. The influences of deepening the financial capital on the quality of economic growth are investigated by means of the estimation method of system GMM model. The results show that the current scale of capital supply has inhibitory effects on the quality of economic growth. The deepening of bank capital and insurance capital has positive effects on the quality of economic growth. The deepening of security capital has no significant effects on the quality of economic growth. There are regional differences in the effects of deepening financial capital on the quality of economic growth.