The PPP(precise point positioning) algorithm based on the single differencing between satellites and the robust Kalman filter model was studied and analyzed. And then, the global position system, global navigation satellite system and BeiDou navigation satellite system data had been used to analyze to the positioning precision and convergence time of single, double and threesystem PPP. Finally, the conclusion were drawn as follows: the positioning precision or the convergence speed of the three-system PPP technology is optimized, and multiple-system integrated navigation and positioning can improve the precision of navigation and positioning.