Abstract: As an important integrant of satellites navigation augment system, receiver autonomous integrity monitoring refers to monitor the integrity of user positioning result based on redundant observations. Precise Point Positioning（PPP）is one of the key technologies in GNSS high precise positioning. In this paper, extended kalman filtering estimate is adopted in PPP, the estimated parameters including station coordinates, receiver clock offset, tropospheric delay and virtual parameters. Based on parity method, correlation distances of design matrix vectors are mainly studied and taken as research objects of detection and recognition of gross error. The set of single and multiple gross errors can be distinguished by using the correlation distances time series of vectors and matrix. The RAIM method of PPP proposed in this paper, solves the issue of quality control and have the characters of simple and easy understanding. It makes the recognition of gross error more clear and can detect multiple gross errors.