Selecting the trading information of corporate bonds with the credit rating of AAA and treasury bonds in China’s bond market on a monthly basis，and solving the Svensson ( 1995) model of term structure of interest rates through genetic algorithm，the paper gives more exact yield curves of both types of bonds and derives the credit spreads． After time series analysis of China’s bonds with different terms of maturity，it can be concluded that all the credit spread series have one unit root and show the characteristics of autoregressive and moving average． The Ｒ-squared of AＲMA model gives better fitness than the multiple linear regression model． The VAＲ model can fit the dynamic relationship among credit spreads well． Impulse response analysis implies that the shock from other series of credit spreads to one sequence of credit spread will result in severe fluctuations with low magnitude in the first 10 terms and the impact does not have long and continuous effect． The empirical results provide the basis of decisions for investors and regulators to some extent．