Application of hydrostatic leveling system in key scientific engineering and its developing tendency

This paper summarizes the basic principle of the hydrostatic leveling system and technologies used in the worldwide. It emphasizes on the introduction of the international application and development of HLS used in key scientific engineering, especially in electronic accelerators, and the researching background of the new type of HLS for BEPC II. By the introduction, the author also hopes to unify the English name of the hydrostatic leveling system in China, with an aim to be identical with the name internationally used. (authors)