Abstract: The error of single point positioning by single-frequency pseudorange is hard to eliminate, especially the ionospheric error does. In order to eliminate those errors, this paper analyzes the composition of the pseudo-range error and proposes the self-differential method between the epochs using the time correlation of the errors to eliminate them.In view of the problems of large broadcast ephemeris error and precise ephemeris not real-time, this paper corrects the satellite position deviation and the deviation of the clock difference obtained by the broadcast ephemeris, through the broadcast ephemeris correction information provided by IGS.In this paper, the characteristics of the self-differential method between epochs are analyzed. It is found that the epoch interval and the initial point precision have great influence on it, and the viewpoint is verified by the measured data.In addition, by comparing with the conventional single-frequency pseudo-single point positioning, it can be seen that the three-dimensional positioning accuracy is about 1.2 meters at a time interval of one second, and the positioning accuracy is greatly improved.