Abstract: According to the problem that the basic horizontal control network (CPI) of high-speed railway is updated continuously at multiple points during the operation period, resulting in a large number of updates of encrypted route horizontal control network (CPII) on high-speed railway line, a new method of updating CPI points based on stable CPI and encrypted CPII as constraint points is proposed. The engineering application shows that the proposed new method can better match the current situation of high-speed railway in the operation period, and reduce the renewal rate of encrypted CPII on the high-speed railway line; compared with the traditional methods, the results show that the update rate of the proposed new method is reduced by 7.3%, which verifies that the algorithm has great application value in the update calculation of encrypted CPII of high-speed railway.