The relative contributions of the local and remote atmospheric moisture fluxes to summer precipitation over Songhua River Basin and its interannual variability are investigated using Brubaker model in this study. Climatologically, due to the prevailing westerly wind in early summer (May-June), the remote atmospheric moisture is the dominant contributor to early summer precipitation, which accounts for 78.9%. Accordingly, the local evaporation contribution is 21.1%. In late summer (July-August), the East Asian summer monsoon brings more moisture via the south boundary, the contribution of the remote moisture increases to 86%, and the contribution of the local evaporation reduces to 14%. JRA-55 can well capture the interannual variation of summer precipitation over Songhua River basin, with the correlation coefficients of precipitation in early summer and late summer for 1961-2016 at 0.73 and 0.83, respectively. It shows that the moisture flux via the southern boundary caused by stronger southwest monsoon plays the dominant role in early summer, and the moisture fluxes via the western and northern boundary are significantly negatively correlated with the early summer precipitation. The contribution of local evaporation is not statistically significant. The moisture fluxes anomalies tend to occur in the early summer with El Ni?o decaying. In late summer, the significantly positive contribution is from the moisture flux via the southern boundary and negative contribution from the local evaporation. The oceanic forcing on late summer precipitation anomaly is not significant, and internal atmospheric variability dominates. The significant negative contribution of local evaporation is due to significant negative correlation between surface temperature and precipitation. When precipitation is less than normal, surface temperature is warmer than normal, thus more evaporation and more contribution from local evaporation to precipitation.