In this study, we assess the ability of the Model AGCM BCC_AGCM2.0.1 to reproduce the precipitation days with different rainfall amount under the atmospheric circulation. By the Cumulative Frequency Distribution (CFD) method, the rainy period in observations is from the fifth pentad of June to the second pentad of July, while the simulated rainy period is from the first pentad to the third pentad of June. Thus the simulation period preceded the observation period by 20 days. Over the YangtzeHuaihe River Basin in general, stormy and heavy rainy days are more, but the moderate and light rainy days are less. Over recent 40 years, as observations indicated, the light rainy days decrease, while the other three rainy days increase. The trend in simulation is opposite to the observation.