As the conventional angular measuring system which uses rotary encoders has the shortcomings of low resolution, large quantization noise and low angular velocity accuracy, a sensor fusion angle measurement method based on fiber optic gyroscope and rotary encoder was proposed. First, the encoder angle signal and the fiber optic gyro rate integration value were subtracted in a sliding window, and the rate drift of fiber optic gyroscope was estimated utilize least square method from the deviation signal. Secondly, the angle was estimated using the compensated angular velocity signal and the encoder signal through a certain combination algorithm. Finally, mathematical simulation and experimental verification were conducted for the proposed method. The results show that the simulation value and experimental value of angle measurement accuracy are improved from 1.2″ and 1.1″ to 0.17″ and 0.76″, respectively. The angular velocity measurement accuracy are also improved from 0.002°·s－1 to 0.001°·s－1. The proposed methed effectively improves the angle and angular velocity measurement accuracy, while avoiding the rate drift problem of fiber optic gyroscope.