The error of rotation table shafting error is the main factor that cause the horizontal attitude demodulation error of single-axis rotation inertial system. To solve this problem, an online high-precision self-calibration method for rotation table shafting error is proposed in this paper, and the propagation model between rotation shaft declination and attitude demodulation error is analyzed and deduced in detail. The error calibration method of shafting of turntable is designed. By using the output data of turntable Angle encoder and IMU gyro, the high-precision calibration of shafting effectiveness of the method is verified by practical data.