To improve the anti-interference ability of the laser interferometry acoustic measurement method, the amplitude modulated laser interferometry is proposed. Using the high-frequency tuning characteristics of a tunable semiconductor laser to modulate the laser signal amplitude, the underwater sound field information is obtained from the interference of the reflected light on the water surface and the reference light. In addition, the phase-locked amplification and demodulation method is used to obtain the laser interferometry underwater sound signal with accurate inversion. The characteristics of the amplitude-modulated signal are simulated, and a fiber-coupled laser interferometry underwater acoustic test system is built. A modulation frequency of 10 kHz is used to drive a pigtail with a center wavelength of 1405 nm to output a tunable semiconductor laser, and the sound signal is tuned down for measurement. Results show that the proposed method can effectively extract the vibration characteristics of underwater acoustic signals with different frequencies and intensities. Under the interference of pulse noise with a frequency of 2 Hz, the proposed method can be used to measure the signal noise better than the traditional measurement method. The ratio is increased by more than 10 dB, which enhances the anti-interference ability of the underwater acoustic measurement.