Abstract: This paper proposed a calibration method with small rotation-angle corrections for the exterior orientations of vehicle laser imaging system. In the vehicle laser imaging system, Mobile Surveying & Mapping Platform system (MSMP), integrated GPS with both IMU (Inertial Measurement Unit) and LS (Laser Scanner), the method uses six small rotation-angle parameters and six small translation parameters to correct the parameters of traditional models. The experiments show that the new method efficiently corrected installation errors and temporal synchronism errors in the system.