Behavior of the monsoon over the South China Sea during the early and late summer is investigated diagnostically. The result shows that there is a distinction in the characteristic features of the monsoon between these two periods of time owing to the different structure of the heating field between early and late summer. In the former period, the monsoon over the South China Sea is mainly associated with the Indian monsoon while in the latter case, the interaction with the Southern Hemispheric circulation becomes prominent.