In the highprecision positioning and orientation system aided by the auxiliary ElectroOptical inertial navigation, the initial alignment installation angle of sensitive axis among systems is the key factor. Based on calibration principle of the installation angle of the sensitive axis, the installation angle calibration is converted to the calibration of the lateral position error. The main factors of affecting the lateral position deviation are detailedly analyzed, and the affection of INS system error and the installation angle are separated. The Lateral position deviation by the installation angle of sensitive axis is calibrated by using the least square algorithm. The simulation results reveal that the calibration accuracy of the installation angle of sensitive axis is less than 10″. Experimental verification result is less than 20″ (1σ). Moreover, the algorithm is simple and convenient to be implemented, less timeconsuming, and small dependency on the external environment. Thus, the highprecision dynamic alignment requirement can be satisfied in this work.