Abstract: It's a better remote high-precision time transfer method that applies the navigation system inter-satellite link to the satellite-ground time synchronization by using the BDS. The satellite-ground time synchronization can offset most of the channel errors through two-way measurement, then improve the measurement accuracy,but there are still some residual errors caused by the inconsistency between upstream and downstream paths,which will diminish the accuracy of time synchronization. This paper introduces the basic principle of time-synchronization,gives the main error correction methods in the process of time-synchronization,focuses on the influence of orbit a priori information on the time-synchronization performance,analyzes and verifies the actual time-synchronization data using different precision orbits.The results show that the RMS values of the residuals of the satellite-ground clock difference fitting solved by using BeiDou broadcast ephemeris and precision ephemeris are better than 0.1 ns,and the time synchronization accuracy can be further improved by smoothing when the orbit data are superimposed with a certain degree of random errors.The research and analysis in this paper can provide some technical reference and accumulation for the realization of high-precision satellite-ground time synchronization.

Key words: inter-satellite link, satellite-ground time synchronization, two-way measurement, error correction, orbit information