Abstract: Facing the problem that in some specific scenarios in port, such as the shore work area and the container yard, the high-precision positioning of unmanned vehicles, this paper uses Cartographer simultaneous localization and mapping (SLAM) algorithm based on reflective targets to solve it. The reflective target parameters and layout method are designed and optimized, and the impact of key parameters inclucling speed and vibration, on the positioning accuracy of laser SLAM based on reflective targets is analyzed. A test system is designed and implemented, and extensive comparison tests are carried out to verify the trend of positioning accuracy. A large vibration can lead to the failure of laser SLAM, which is common in port. Therefore, the mechanism of positioning failure caused by large vibration is analyzed, and the composite positioning technology based on inertial measurement unit (IMU) and laser SLAM is implemented to suppress the positioning error of laser SLAM under a large vibration. The experimental results show that the proposed method improves the positioning accuracy and robustness of laser SLAM for unmanned vehicles in port.