The spatial and temporal features and circulation characteristics of summer prec ipitation anomaly in Sanjiangyuan are investigated on the basis of the monthly r ainfall data at 14 stations from 1961 to 2005. The results show that the spatial distribution of summer precipitation has a good coherence in Sanjiangyuan, and on the whole has decreasing trend in the last 45 years. In addition, Morlet wave let analysis indicates that there were quasitwoyear, quasifourtosixy ear periodi c oscillations in the summer precipitation, and three sudden changes in the year s of 1968, 1979 and 1986 respectively. The above results indicate that the wet/d ry years of climate in Sanjiangyuan are closly related with the height field, temperature field, and w ind field, the relations can obviously be as factors for precipitation’s foreca st.