For realizing the information processing system of GPS/BD-2 compatible navigation receiver，this study established a mathematical model of GPS/BD-2 based on single positioning system，and analyzed the characteristics of dual-system positioning system. In order to decrease the influence of low positioning precision of GPS，a proposal was made that using Weighted Least Square(WLS) method as the basis of position solution. A suit of information processing system was realized based on WLS in C/C++ language. The software process was described and the results were analyzed. The algorithm and software were experimentally validated.