Along with China’s economy development and the deepening of reform and openness, the financial institutions development rapidly and gradually become an important support force to promote the economic development. However, credit risk becomes a quite important uncertain factor that affects commercial banks. In this paper, we analyze the impact of financial system on economic fluctuations by using time series model. The result shows that LnFIR at lag 1 period increased one percentage can drive LnGDP growth by 0.652, LnFIR at lag 2 period increased one percentage can drive LnGDP decrease by 0.217 percentage, so the effect of financial development on economic growth is obvious. In addition, we researches on the performance and characteristics of credit risk under the condition of the macro-economic uncertainty and how the commercial banks prevents credit risk by perfecting systems.