a non;contact angle measurement method based on gyrorotor with periodical pattern surface is proposed. by using photoelectric sensors to detect the information from periodical pattern surface of gyrorotor, we can measure the deflection angle of gyrorotor in real time. the angle measurement principle and its device are introduced. by constructing three;dimensional geometrical models, the angle decoding algorithm of the angle measurement method is derived in detail, and the curves or the surfaces of the relationships between the gyrorotor's pattern surface information detected by photoelectric sensors and the angle deflections (calculated under the conditions that the gyrorotor is without deflection, with one;dimensional deflection and with two;dimensional deflection respectively) are obtained. the results show that the deflection angle and the deflection direction of gyrorotor can be measured by two photoelectric sensors in orthogonal directions, and the measurement values are unique and the measurement range of deflection angle is larger than 30°. this method can be used to measure angle deflection both in static and high;speed dynamic measurements. © 2016, chinese lasers press. all right reserved.