Abstract: The simulation analysis and optimization of a MEMS (Micro-Electro-Mechanical System) piezoelectric vector hydrophone with U-groove or double U-groove are carried out in this paper. The hydrophone chip is prepared by micromachining technology. Finally, the prepared chip is packaged and tested. The comprehensive analysis of the theoretical sensitivity and energy is proposed to permit the accurate structure optimization by considering the impact of stray capacitance. From the acquired experiment results, it is divulged that the employed optimization method exhibits a higher accuracy than the traditional optimization approach, which takes into account only the theoretical sensitivity. On top of that, the sensitivity of the proposed double U-groove structure is about 5.9dB higher than that of the single cantilever structure, and it has good directivity.