In order to improve the operational performance of vehicle-mounted electro-optical system,the influence factors and error sources of the system tracking accuracy are analyzed.Then according to the producing conditions of the error,the calculation formula of system error and random error are deduced.Taking a certain electro-optical system as an example,a method to improve the tracking accuracy and compensation was proposed through analysis and calculation.The results show that the azimuth system error,the elevation system error and the random error of the system are 0.325 mrad,0.283 mrad and 0.276 mrad respectively,and the results are all less than 0.5 mrad,which meets the requirement of technical index.