Because of the characteristics of BDS satellite constellation and the accuracy of satellite orbit and clock error,the initialization time of the traditional ionosphere-free combination precision point positioning (LC-PPP) is longer.To solve this problem,we use the Zero-difference Zero-combination PPP (ZDZC-PPP) algorithm to quickly initialize BDS PPP.Due to use the zero-difference zero-combination observation can take advantage of a priori information of ionosphere delay as a prior restraint to enhance the strength of the equation,so that it makes it possible to shorten the PPP initialization time.This paper introduces the ZDZC-PPP algorithm,and analyzes the difference between it and the LC-PPP.Compared with the traditional LC-PPP,the calculation results show that the ZDZC-PPP can effectively shorten the initialization time and can obtain the high accuracy of the positioning results by MGEX observation data.