In this paper, the structure of an acoustic sensor based on optical FP cavity is designed, its sensing principle is analyzed, and its key indexes are tested by experiments. The experimental results show that the sensitivity of the sensor remains in the range of -119.98 ~ -120.99 dB re 1 rad/μPA in the range of sound wave frequency of 5 ~ 1000 Hz, and the sensitivity change is less than 1.01 dB, with a wide response flat range; It works stably at the frequency of 150 Hz and the sound pressure of 0.18 ~ 5.30 Pa, and there is a good linear relationship between the sound pressure and phase.
