The automatic docking process of connector and rocket valve is studied, and a bias measurement system based on dynamic azimuth detection alignment technique is proposed. The deviation value of the connector with the fill valve is obtained and defined as the initial value. The image of the cooperative target is obtained by the optical camera. The camera pose in the two-dimensional plane is quickly extracted by identifying the direction of the target image and the marker size; and the laser sensors are used to accurately obtain the distance information between the target and the camera. The deviation value between the connector and the fill valve can be obtained in real time through this measurement system. It is applied to the automatic docking system, and the results show that the method meets the technical requirements of the automatic docking displacement accuracy 1 mm of the rocket.