A novel approach to calibrate PIGA (Pendulous Integrating Gyro Accelerometer) on three-axis turntable is presented in the paper. The approach can separate and attenuate the impact of friction moment of outer gimbal and alternating moment caused by the intersecting acceleration on the accuracy of accelerometer. By the new methods of accelerometer input axis misalignment, the error angle of accelerometer is reduced and the calibrating accuracy of accelerometer is increased.