Mobile mapping technology provides an efficient means of data acquisition, which can be used in many areas such as smart city construction. It is an advantage to integrate 3D laser scanner into MMS for the feature of quick speed and high accuracy. The mounted parameter calibration of 3D laser scanner had been studied and three improvements were made on the existing calibration method. Firstly a simpler mathematical model was put forward to reduce the calculation complexity. Secondly, man-made targets of retro-reflective material were used to improve calibration accuracy. Lastly one-station calibration scheme was adopted to improve the efficiency. According to the measured data, the calibration accuracy of the method was 6 mm, and the overall design accuracy of the system is 5 cm, so the scheme can meet the requirements of the accuracy of the vehicle system.