A relative navigation method based on INS/Vision is presented with the consideration of the measurement of vision navigation equipment with time delay,and the relative inertial equation between the leader and the follower is derived.The line of sight measurement is acquired by observing the beacons on the follower using the vision navigation equipment on the leader.The extended Kalman filter is used to estimate the relative attitude,relative velocity and relative position by fusing the inertial navigation information and the line of sight measurement.For the time delay problem of vision navigation equipment,a method of fusing the inertial navi gation information and the measurement with time delay is provided.Simulation results verify the effectiveness of the relative navigation method.