Abstract: Low Earth Orbit Satellite (LEO) has the advantages of rapid change of geometric configuration relative to the ground and low loss of broadcast signal link. With the gradual reduction of low orbit satellite load development and launch cost, low orbit satellite navigation enhancement technology has become a research hotspot in the field of satellite navigation. At present, the research on LEO navigation enhancement technology at home and abroad is in its infancy. There is no mature LEO navigation satellite constellation, and there is no effective means to verify the service performance of LEO navigation enhancement system. In this paper, the orbit extrapolation method of LEO navigation satellite and the signal acquisition and tracking technology of LEO satellite are studied, and the semi-physical simulation platform of LEO navigation enhancement system is designed and constructed. On the basis of the simulation platform, the high-precision fast precision positioning method of the combined application of BeiDou / LEO enhancement system is verified, which realizes the rapid convergence of precision single point positioning (PPP) and has high internal coincidence accuracy. It has certain scientific and engineering value for the construction and application of LEO satellite navigation enhancement system.