The main principle of the existing optical gyroscope is based on the Sagnac effect. How to improve the measurement accuracy of the Sagnac effect is an important research topic of improving the gyro accuracy. The traditional optical gyro uses the short wavelength characteristic of light to improve the detection accuracy. But when considering the fact that the detection accuracy of the microwave phase/frequency is much higher than that of light wave phase/frequency, if the microwave can be used to detect the Sagnac effect, the detection accuracy higher than optical gyro accuracy can be obtained, which makes it possible to achieve high-accuracy microwave gyro. The Sagnac effect is detected by using the optoelectronic oscillator based light-carrying microwave structure. Experimental results prove the feasibility of detecting Sagnac effect by using microwave, which lays the foundation for realizing the high-precision microwave resonant gyroscope in the future.