Submarine Groundwater Discharge(SGD), an important part of global water cycle, is recently recognized as a research highlight on the landocean interaction in the coastal zone. Firstly, This paper analyzes the components and driving force of SGD, and summarizes the main estimating methods of SGD and its individual strengths and weaknesses. Secondly, the paper describes the important role of SGD in transporting dissolved mass into the costal ocean and significant impacts on the ecological environment of costal ocean, and through analyzing the biogeochemical process in the mixing zone of freshsalt water, indicates the important position of subterranean estuary in studying submarine groundwater discharge. Finally, the paper points out the major problems currently existing in SGD research, then presents the future research direction.