As the importance flight control parameter of the four rotor aircraft, attitude angle played an important role in stable flight. For gesture detection problem, attitude detection system was built with STM32F407VG, MPU6050 and AK8975. Spacecraft attitude was described using quaternion method, and the data of the accelerometer and the electronic compass were optimized by using the conjugate gradient method, then the data fusion parameters were used to correct the gyro drift error, so as to achieve the best fusion effect. Results showed that the detection and data processing system was simple, reliable, stable, easy to calculate and could satisfy the requirements of the accuracy and instantaneity of four rotor aircraft.