Aiming at the problem that the attitude calculation algorithm based on the Inertial Measurement Unit (IMU) is noisy, has low accuracy and cannot accurately calculate the attitude angle variation in the yaw direction, a MARG sensor system attitude calculation method based on the conjugate gradient algorithm is proposed.The accelerometer and magnetometer are used to measure the attitude error, the conjugate gradient algorithm is used to compensate for and correct the gyroscope attitude quaternion, and the data is weighted and fused to obtain the aircraft attitude quaternion.A three-axis turntable is used to verify the stability and accuracy of the algorithm.The results show that the algorithm can effectively suppress measurement noise and improve the accuracy of attitude angle calculation.