Under the environment affected by non-gravitational external force, the pose measurement of a 6D laser target becomes invalid. In order to solve this problem, a pose measurement method based on laser target combined with strapdown inertial navigation system (SINS) is proposed. By deriving the Kalman filtering state equation and observation equation, Kalman filtering model of combined measurement system is established. The pose error and the random error of the inertial measurement unit (IMU) are both corrected by the Kalman filtering. The fault detection method is introduced into the Kalman filtering model, so that the combined system achieves the ability of self-monitoring. When the pose data of the laser target become invalid, the system can only use the corrected SINS data to ensure the reliability of the system. Finally, the method is verified by the simulation experiment. The simulation results show that this method can effectively solve the invalid problem of pose angle measurement of the laser target and improve the anti-interference and dynamic performance of the system.