Abstract: The time comparison with by means of synchronous satellite is a commonmethod, which has the advalltages of low cost, simple operation and wide scopeof service. The key technique for raising the precision of time comparison withthe method is to determine and predict the orbit of synchronous satellite moreaccurately Based on the improvement of the previous program for orbit determination and prediction, further in vestigations concerning time comparison using thismethod is conducted in this paPer. The experimental results show that the post-processing precision of time comparison obtained with the new program is aboutthe same as that obtained with the previous program, which is better than 1 ps,but the pre-processing precision has been raised greatly as compared to that olytained previously With the new program of orbit determination and prediction, thepre-processing precision of time comparison can keep better than 1 ps in one week.