Precipitation intensity of East Asian summer monsoon in the 20th-century simulations by the Atmosphere-Ocean General Circulation Model (AOGCM)s was evaluated. Eighteen AOGCMs were selected from models contributed to the Intergogermental Panel on Climate Change (IPCC) 4th assessment report (AR4). The one-degree daily precipitation data of Global Precipitation Climatology Project (GPCP) compiled by Huffman et al. (2001) were used for verifying simulations. GPCP daily data cover 7 years from year 1997 to 2003. Ten-year daily precipitation data from year 1991 to 2000 were collected from the 20th-century simulations. As a measure of precipitation intensity, we used the Simple Daily precipitation Intensity Index (SDII) which is defined as the total precipitation divided by the number of rainy day (rainfall greater than or equal to 1 mm/day). SDII was calculated for 2-month period from June to July corresponding the main East Asian summer rainy season. In general, models underestimate the magnitude of SDII compared with observation. However, higher horizontal resolution models tend to perform better than lower resolution models do. The effect of implementing flux adjustment on the model performance is not consistent and straightforward.