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 Al_0.8Sc_0.2N 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