Abstract: We developed a new method of single-frequency precise positioning for the users in a large region. Compared with current methods, this new method avoids selecting designated static reference network, it has been proved to be effectively modeled on the ground instead of be modeled at 350 km above the ground (as is shown by SEID), and the calculation of the maximum-modeling difference is also given. The results show that for an ionosphere\|active region of 100 km×100 km, where there are at least 3 dynamic reference stations, user can get cm-level position accuracy in the horizontal direction with 20 minutes observation data. Furthermore, this method provides a new way on the research of single-frequency precise positioning.