Abstract: Numerical experiments based on a low resolution AGCM were developed to investigate the influence of SSTA over the South China Sea (SCS)-Eastern Tropical Indian Ocean on the South China Sea summer Monsoon (SCSM). The results show that, with positive SSTA, the strong anomalous cyclones at 850 hPa and anomalous anticyclones at 200 hPa exist symmetrically about the equator around the test region, and the anomalous convergence in low layer and divergence in high layer occur over the SCS-West Tropical Pacific, exceeding the 95% significance level, the spatial pattern of the anomalous circulation resembles to the theoretical solution of Gill; with negative SSTA, almost opposite anomalous circulation can be found in the experiments, but the anomalous convergence in low layer and divergence in high layer decrease and moves northward, the anomalous convergent centers near equator beside its south side both in low and high layer develop and move northward, which enhance the Monsoon meridian circulation. Corresponding to the warmer SST, the low level anomalous cyclones on both side of the equator will weaken the Somalia and Australian cross-equator SW flow, but strengthen the equator westerly flow, the anomalous anticyclones over eastern Phillips will strengthen the Subtropical High with its ridge extending south-westward, and the high level anomalous anticyclones on both side of equator will strengthen the South Asia High, which will weaken the SW flow going into SCS, hence weakening SCSM and delaying its onset; Corresponding to the colder SST, the low level anomalous anticyclones on both side of the equator will strengthen the Australian but weaken the Somalia cross-equator SW flow, the anomalous cyclone in northeast of Phillips will decrease the Subtropical High, the stronger monsoon meridian circulation over the Western Tropical Pacific will strengthen the Australia across equator SW flow, and the high level anomalous cyclones on both side of the equator will weaken the South Asia High, which will push the SW flow enter into SCS, hence strengthening SCSM and speeding its onset.