Sea level change is a part of global climate system change. It is an important indicator of environmental change and affects the ecological environment of coastal areas and islands. Global sea level change is composed of sea water mass change and steric sea level change. The change of sea water mass is mainly caused by the water produced by melting of polar ice sheets and glaciers in high mountain areas flowing into the ocean; the steric sea level change is caused by the change of sea water temperature and salinity, while the temperature variation is the most important factor. The study of sea level change is of great significance to science and society. For a long time, scientists have paid close attention to this issue, carried out a lot of research and made important progresses. This paper describes the development of various monitoring technologies for the sea level change and summarizes the research status of sea level change. All the research results shown that the global mean sea level has been rising for more than 100 years. In recent decades, the sea level has been rising faster and faster. There are still some problems, including (1) people have not fully understand the law of sea level change and there is a great uncertainty in the prediction of future sea level change; (2) measured data in deep sea are not enough; the law of ENSO and its impact on sea level is still not clear; (3) land and ocean signals in GRACE cannot be completely separated and the consistency analysis between GRACE and GRACE-FO needs to be developed. These problems need to be further studied.