The rainfall prediction with AREM (Advanced Regional Eta Model) under the background of T213 analysis and AVN (Aviation) analysis fileds from 1 June to 31 November 2005 is analyzed. The daily average deviation and root meansquare standard deviation of the two analysis fields are computed, and the distribution of the deviation is analyzed. The results show that keeping the other conditions the same, there is obvious difference in the rainfall prediction of AREM between two background fields; as a whole, the prediction is better under the background of AVN analysis field than under T213 analysis field; contrasting the two analysis fields statistically, there were obvious differences in height, temperature and relative humidity, and big deviation over Siberia north of Xinjiang, the northeastern part of Mongolia and the southeast part of Russia, the Bay of Bengal, and the QinghaiXizang Plateau. The weather systems in those areas have important effect on the weather in China.