This article presents a high performance piezoelectric MEMS acoustic device for hydrophone applications, which consists of 5×5 circular arrays with a diameter of 200 μm, and the size of the device is 3 mm×3 mm. The piezoelectric coefficient of AlN films is enhanced by using scandium doping with a mass fraction of 20%, and the electrical signal output under acoustic pressure is enhanced by a two-electrode structure configuration and optimized structure size to achieve better reception sensitivity of piezoelectric MEMS acoustic wave devices. The acoustic device has a receiving sensitivity of -166.8 dB (Ref.1 V/μPa) in air, which is about 2.6 dB higher than that of the same structure based on AlN film. The device has a flat acoustic response with a sensitivity curve change of less than 1.5 dB in the bandwidth range of 50 Hz to 3 kHz. The results show that the piezoelectric MEMS acoustic wave device based on the Al0.8Sc0.2N film has higher receiving sensitivity, and the hydrophone sealed by the watertight package can be used for pipeline leakage detection, marine noise monitoring and other engineering applications