After studying the geometrical relation of the reflection signal (GNSS-R) of the global positioning satellitesystem and its specular reflection point algorithm, and determining that the problem is a one-dimensional single-peak function extreme value search problem, a GNSS-R specular reflection point estimation algorithm based on the advance and retreat method was proposed.The feasibility of advance and retreat method in estimating specular reflection points is discussed.In order to verify the correctness of this algorithm, MATLAB simulation software is used to analyze the algorithm and the traditional algorithm.The simulation results show that the advance and retreat method can correctly estimate the position information of GNSS-R specular reflection point, and has the characteristics of fewer iterations and faster operation speed.