The paper quasi-quantitatively analysed the characteristies of seasonal variation of mean sea surface temperature (SST) in the kuroshio region and its physical processes. This study showed that not only the heat budget through the sea surface was possessed of an important influence for variation of SST, but also advectional heat transfer, and horizontal diffusions inter water cann't be neglected. The order of magnitude of heat transfer term was estimated respectively. Based on mentioned above the relationship between the asymmetrical variation of SST and atmospheric circulation was discussed. From the results of the above relationship, the atmospheric circulation in winter had significant effect on the asymmetrical variation of SST.