In modern war, the environment of war field is worse than before, so single mode guidance is prone to be influenced by weather, jamming etc. These bring adverse effect on guidance performance and adaptability. The advantage of each sensor is used by radar/IR mode in guidance to improve the anti-jamming ability and tracking precision. Based on the project, at first the metrical information of radar seeker and IR seeker was fused through the method of adaptive variance. Then, EKF was used to estimate target motion. Finally, the ballistic simulations were presented to verify the validity of this method.