This paper reviews the economic situation of China in 2019 at first，and then analyzes the origins of economic growth through the growth theory as well as related empirical test. Based on the decomposing of the contribution of various factors，the paper analyzes and forecasts the potential of economic growth of China in mid-and-long-term，as well as the tendency. The conclusion is that China can still maintain a mid-and-high growth rate in the coming 15-20 years，and will fulfill the task of modernization by 2035.