Abstract: Using data from Hong Kong GPS active network, we found that there was a strong ionospheric activity in Hong Kong in March 2001 and it is difficult to resolve GPS ambiguity by conventional positioning method in most of the daytime. In this paper a data process strategy for GPS rapid static and real time kinematic positioning using GPS reference network has been presented. Using this method, we can generate network correction of either DD ionospheric delay or DD residual using the reference network. After applying these corrections to a user, both the positioning accuracy and the success rate for ambiguity resolution have been significantly improved.