In order to improve the precision of celestial positioning system, and decrease the influence of the inclinometer installation error on the level measurement, the calibration and correction of the installation parameters of inclinometer in celestial positioning system were studied. First, the working principle of celestial positioning system based on inclinometer was presented, and the error sources in the installation process of inclinometer were analyzed. Then, a method for calibrating the installation parameters of inclinometer was proposed by transformation of celestial positioning system, and the correction algorithm of inclination measurement was presented. Finally, the simulation platform of three fields of view celestial positioning system was established, and the performance of the calibration method was analyzed and verified. Experimental results indicate that the calibration accuracy of the installation parameters of inclinometer is consistent with the accuracy of the sensor, and the maximum error of the inclination measurement is 4.315 5″ in full-range, which can satisfy the requirement of the high-precision level measurement of celestial positioning system.