Internal tide is a kind of internal wave found frequently on the continental shelf. It is often generated by the barotropic tide crossing special topography in special ocean state. Therefore, the internal tide has the tidal period. Frequent internal tide can be of advantage or disadvantage to the human activity in the ocean. For instance, it can drive strong mixing or even generate upwelling bringing nutrition up from deep water so that a fishing region can come into being. On the other hand, internal tide with large amplitude and generating solitary waves will disturb the work of oceanic engineering and be dangerous to marine oil platform and submarine oil pipe. The turbulence driven by internal tide can also affect the ship or submarine, and reduce the precision of torpedo. So, the observation on the internal tide near the continental shelf has been emphasized for long. This paper will make a brief introduction about some characteristics of internal tide, and discuss the evolution of the observation in recent years. As a stress, the present situation of study of internal tide in the northern south China sea will be described, questions of observation on the internal tide in the South China Sea discussed some opinions about developing the study and observation on the internal tide put forward.