In order to study the Doppler positioning performance of low-earth orbit communication satellite, this paper analyses the ground coverage characteristics, signal transmission characteristics and Doppler frequency shift characteristics of low-earth orbit satellite, deduces the Doppler positioning principle and method and proposes the geometric dilution of precision which is suitable for Doppler positioning, firstly. Then, based on the Iridium satellite and GlobalStar satellite system, the number of visible satellites and geometric dilution of precision are calculated, and the positioning simulation experiment and error analysis of the corresponding stations are carried out. The results show that as for Iridium and GlobalStar systems, the visible number of satellites decreases and the Doppler geometric dilution of precision increases with the decrease of latitude; the accuracy of Doppler positioning results is affected by the frequency measurement accuracy, satellite position error and satellite speed error at the same time. When the satellite position error is less than 10m and the satellite speed error is less than 0.1 m · s^-1, it has little impact on the positioning results. At this time, the frequency measurement accuracy becomes the decisive factor affecting the positioning accuracy, and when the frequency easurement accuracy is 0.01 Hz, the positioning accuracy can reach 1.18 m.