Balancing the piezoelectric coefficient and carrier concentration of materials is a key in the field of piezocatalysis. In this work, Bi₂WO₆ material with both piezoelectric and semiconductor properties was chosen as a model material. One-step ethylene glycol-assisted solvothermal method was used to synthesize Bi₂WO₆ with oxygen vacancies. By controlling solvothermal time and temperature, the oxygen vacancy concentration (C_OV) was regulated. As the C_OV increases, the piezoelectric coefficient decreases, and the carrier concentration increases, the hydrogen production rate increases at first and then decreases. When the C_OV reaches 1.45×10¹² spins mg^–1, the corresponding piezoelectric coefficient and carrier concentration values are 13.9 pm V^–1 and 2.90×10²⁰ cm^–3, respectively. The optimal hydrogen production rate per power of 2.21 μmol g^–1 h^–1 W^–1 is equivalent and even better than that of most reported piezocatalysts. The piezoelectric coefficient and carrier concentration as two factors jointly determine the piezocatalytic performance. The findings in this research can provide important and deep-seated insights for better piezocatalysts in future.