To solve the problem of the radar seeker measure deviation, the influence of sea surface multipath effect on ship-air missile radar seeker is researched. From the technique principles of multipath effect, according to the position of radar seeker and target, the model of multipath effect was built, use simulation method, the influence of target flight height and grazing angle on radar seeker tracing angular deviation was analyzed. The simulation result shows the test provided a reference for radar seeker to reduce multipath effect.