Resonant fiber-optic gyro（ R-FOG） is a high-precision inertial sensor which use optical Sagnac effect to achieve rotation angular velocity detection. Theoretically analyze characteristics of sine wave modulation

built a modulation and demodulation test system of optical micro resonant cavity

then experimentally compare influences of three modulation waveform

respectively the sine wave

sawtooth wave and triangle wave

on signal to noise ratio of resonance signal

the effect of the sine wave modulation is the best and signal to noise ratio of resonance signal is improved. Test influence of sine wave modulation on resonance signal in condition of different modulation amplitude and frequency

and derive effect of modulation amplitude and modulation frequency on resonance signal.The result provides a reference for optical microresonant-cavity to select the best parameters of phase modulation in the resonator gyroscope system applications.