Micro Position and Orientation System (POS) is the motion compensation equipment of airborne remote sensing system, which is composed of Inertial Navigation System (INS) and Global Navigation Satellite System (GNSS) with double antennas. The INS/GNSS integrated navigation is the key technology to measure micro POS motion information. However, the installation error angle between INS and dual antennas will seriously reduce the navigation accuracy. To solve this problem, an improved integrated navigation method of micro POS based on installation error angle calibration is proposed. Firstly, the calibration method of installation error angle based on a high-precision POS and the dual antennas is presented. Then, the improved real-time navigation algorithm based on error angle compensation is established. Finally, the flight experiment results indicate that the proposed method can effectively improve the navigation accuracy compared to uncalibrated method, especially the attitude and velocity accuracies, which are improved by 36% and 27%, respectively.