Abstract: To satisfy the construction of CHINA Real-Time Precise Positioning Service System, a method of orbit determination of navigation satellite based on priori global information (predicted orbit) is developed. The key is that how the weighting matrices of priori information are computed. Firstly its mathematic model is expressed. Then the characterization of predicted orbit error is analyzed, and a method of achieving the priori information's weighting matrices by Gauss-Markov process is addressed. At last orbit is determined combining the priori information and regional tracking stations' data. Experiment proves that this method is feasible and gets relatively encourage result.