Abstract: In GPS Precise Point Positioning (PPP), besides precise positioning, the convergence time and stability are important items in GPS kinematic PPP. There are many factors which may affect it, such as the quality of GPS observation, sampling intervals, parameters estimation model, satellite geometry distribution and accuracy requirement and so on. The effect of different sampling intervals of observations, Satellites Clock Bias (SCB), and different positioning precision on convergence time of kinematic PPP is discussed deeply in this paper. Taking GPS observations from twelve GPS reference stations in Shanghai GPS network as an example, we analyzed the relationship of sampling intervals, positioning precision and convergence time. The convergence time of different sampling intervals is analyzed statistically. The results of the analysis are given in the conclusions.