Analytical algorithm for inter-satellite visibility is essential for quantitative analysis of constellation visibility characteristic, which is important for the design of inter-satellite link (ISL) assignment scheme and the design of satellite network topology of autonomous navigation system. Analytical algorithm of inter-satellite visibility is necessary for a satellite to assign ISL autonomously with others. Based on the restriction of scanning range of satellite annular antenna, this study introduced the rules to decide satellites' visibility. According to the Walker constellation's spatial structure and satellite's motion law, it introduced an analytical algorithm of satellite's visibility with satellites in the same obit and different obit. Using the algorithm above to analyze satellites' visibility in Galileo constellation, the simulation results show that in the same and different obit plane each satellite has four visual satellites under the elevation restriction of ［25°, 65°］. The algorithm is also available for the analysis of other circular-like constellation.