In this paper, the authors used a simple hydrothermal method to prepare m-Bi2O4, and also used XRD, XPS, SEM, TEM, UV-vis DRS, PFM and other characterization methods to analyze the structure, morphology, surface valence and piezoelectric photocatalytic performance of the samples, and tested the piezoelectric photocatalytic activity of the material using sulfamethazine (SM) as a simulated pollutant. The results show that m-Bi2O4 has higher catalytic performance than BaTiO3 and BiOCl. After 60 min of the synergistic action of the piezoelectric, the degradation efficiency of the m-Bi2O4 to the SM is up to 96.46%. By changing the wavelength of light, it is confirmed that m-Bi2O4 still has high catalytic activity under the condition of light energy weakening. In addition, base on that capture experiment of active radicals, superoxide radicals with high oxidation activity and a small amount of hydroxyl radicals and singlet oxygen were produce in the reaction system. A possible mechanism of piezoelectric photocatalysis was proposed.