It is expounded firstly in this paper that a kind of foreign originated planetary fortune-telling system was accepted and applied widely between late Tang Dynasty and early Song Dynasty in China. It is also explained that the calculating of the planetary ephemeris, which was an important handbook for fortune tellers, then became a necessary technical support by astronomy for astrology. It is pointed out finally that this kind if support could be provided by some astronomers or astrologers proficient in the astronomical calculation, and the calculation of the positions of celestial bodies obtained a quite high precision, according to a detailed investigating to a number of specific fortune- telling cases between late Tang and early Song period.