In this paper, the GLONASS system is introduced, then the coordinates adopted in both GLONASS and GPS are discussed. The authors present a mathematic model of conversion between PZ-90 and WGS-84.This paper lays emphasis on the expounding the solution of converting parameters,then,the converting formula suitable for use in China is also presented. After that, in this paper starting from the converting formula to discuss the WGS-84 ground coordinate system and space-ground coordinate system as well as the PZ-90 space-ground coordinate system and ground coordinate system are discussed.Finally, the data used in China in the process of WGS-84 converting into PZ-90 are analyzed.