For the monitoring requirements of water sublimator, a fiber optic acoustic vibration sensor is developed based on the Fabry-Perot interference microcavity. The low temperature resistant polymer film material is used to make a ultra-thin diaphragm by stretching around as the sensitive components to detect acoustic vibration information and reflecting surface of interference microcavity. The diaphragm is 1.2 μm in thickness. The sensitivity of system is 93 mV/Pa, and the linearity is up to 99.8%. A relatively flat frequency response is achieved from 1 kHz to 20 kHz. The monitoring experiment of water sublimator in the space environment simulator show that the sensor can survive in space environment where the temperature is below 77 K, and detect the real-time acoustic vibration signals generated by spewing ice when the water sublimator is going wrong.