The accuracy of the attitude information of the quadrotor directly affects the flight control effect of the aircraft.This paper introduces the attitude calculation principle of the fusion algorithm combining gradient descent with complementary filtering and the adaptive complementary filtering algorithm commonly used in quadrotor aircraft.The static and dynamic filtering effects of the two algorithms are measured and compared in an independently-developed IMU system.The experimental results show that the adaptive complementary filtering algorithm is superior to the fusion algorithm of gradient descent and complementary filtering on filtering effect in both cases.