Abstract: With improvement of the automatic control technology of the highly mobile radar antenna vehicle, the system accuracy requirements for the measuring instruments such as the horizon sensor and the orientation device are increased, too. The system calibration is very important to make full use of the performance of the measuring instruments and avoid accuracy loss for improper operation. In this paper, based on the practical application of the vehicle-mounted mobile radar, the installation requirements and calibration methods for the horizon sensor and the orientation device frequently used at present are introduced, the calibration steps are described in detail and the approach to remove the inherent system error is discussed. The correct operation of this kind of instrument is given from levelness and azimuth to achieve the expected accuracy.