When the attitude calculation of the quadrotor is performed in a magnetic interference environment,the attitude calculation accuracy will be affected.In order to reduce the influence of magnetic interference on the pitch angle and the roll angle,an improved method based on Extended Kalman Filter (EKF) is proposed.First,based on the EKF,the measured value of the accelerometer is used as an observation to solve the pitch angle and the roll angle.Then,the measured values of the accelerometer and the magnetometer are simultaneously used as an observation,and the EKF is used again to solve the yaw angle.In the second EKF solving process,an adjustable variance measurement matrix is added to adaptively change the Kalman gain,adjust the observation to correct the state prediction,and reduce the influence of magnetic interference on the yaw angle.Finally,the algorithm is verified based on the self-developed flight control system.The verification results show that the proposed algorithm can improve the attitude calculation accuracy of the quadrotor in a magnetic interference environment and the anti-magnetic interference performance of the quadrotor attitude fusion algorithm is enhanced.