By using the model of Xie and the NOAA OLR data in NSMC, the monthly precipitation amount in 1991-2008 was calculated in the area of 10°-60°N, 75°-150°E land with data resolution of 0.5°×0.5° latitudelongitude. Therefore we know that monthly precipitation amount could be calculated out by using monthly OLR anomaly.By comparing the model monthly precipitation with gauge precipitation from NCEP in 1991-2008,we obtained the following results:in winter the relative error in China was 49.14% and the absolute error was 7.97 mm; in spring they were 37.60% and 14.97 mm; in summer they were 27.37% and 31.6 mm; and in autumn they were 37.99% and 16.95 mm. The results were not very good.The main errors were caused by stratus cloud precipitation and continuous cloud cover days without precipitation.By analyzing cloud classification products of FY2C during 2006-2008,we have learned that in winter stratus clouds are common in southern China, and the monthly OLR anomaly there is usually high, and the estimation of precipitation amount obtained from global coefficients A and B is lower than that of ground observation. Therefore, the better way to solve the problem of precipitation underestimation may be in the choice of new coefficients A and B for different areas of China in different seasons.