In order to solve the lag problem of the laser beam-riding missile attacking moving target, a laser beam-riding guidance system without lag is proposed. Based on the missile dynamics model and the target kinematics model, the movement of the missile and the rotation law of the laser beam are estimated using kalman filter technique, a additional compensation acceleration order is generate, which is added to the missile control orders. The simulation result show that the beam-riding system without lag can solve the problem of the lag when the missile attacks a moving target.