Based on the monthly mean global data from CMIP5(Coupled Model Intercomparison Project Phase 5),this paper studies relationship between sea surface temperature(SST) variation and precipitation variation over tropical Pacific and Indian Ocean along with its possible causes from the point of seasonal variation.The ensemble mean results of 20 models show that,under the background of global warming,annual spatial distributions of SST and precipitation variations over tropical Pacific Ocean accord with the "warmer-get-wetter" mechanism.However,the differences between seasonal mean and annual mean are obvious.Both zonal and meridional positional deviations between the local maximum enhanced SST and increased precipitation are detected in winter and spring,but only opposite meridional deviation is detected in summer and autumn.Meanwhile,the similar positional deviation between SST and precipitation exits over tropical Indian Ocean in winter and spring as well.Moreover,seasonal changes of precipitation over two tropical oceans accord with both the "warmer-get-wetter" mechanism and the "wet-get-wetter" mechanism.