The doping of ionic group composed of various atoms can play a great role in regulating electronic structure, optimizing light absorption capacity, and enhancing the catalytic performance of semiconductor catalysts. Herein, we took a urea-precipitate assisting hydrothermal route for preparing PO4-doped Bi2WO6 nanoplates and discussed the effect of the ionic group doping on the sonophotocatalytic performance toward the degradation of pollutant. The result of the X-ray photoelectron spectrometer (XPS) measurements revealed that abundant oxygen vacancies were formed in PO4-doped Bi2WO6 owing to the incorporation of the ionic group, which would contribute to the regulation of electronic structure and activated carriers’ migration rate. The sonophotocatalytic activity toward the removal of tetracycline hydrochloride (TCH) was investigated under visible-light coupling with ultrasonic irradiation. The results showed that PO4-doped Bi2WO6 nanoplates possessed higher sonophotocatalytic degradation rate than pure Bi2WO6. More interestingly, the TCH removal efficiency was continuously improved over PO4-doped Bi2WO6 nanoplates with the assistance of the sulfate radical-mediated technique. Based on the comprehensive discussion and analysis, a possible enhancement mechanism of the sonophotocatalytic behavior was proposed for PO4-doped Bi2WO6 nanoplates catalyst in the presence of peroxymonosulfate.