This study investigates the degradation of tetracycline using dual-frequency ultrasound (DFUS) combined with peroxymonosulfate (PMS). The results show that DFUS significantly enhances tetracycline degradation compared to single-frequency ultrasound. The main reactive radicals involved in the degradation process are superoxide (O₂⁻•), sulfate radical (SO₄⁻•), and hydroxyl (•OH) radicals. The degradation pathways of tetracycline were identified, and the intermediates were found to be less toxic than the original compound. The number of active bubbles in the degradation vessel was calculated using a semi-empirical formula, and a higher value of 1.44 × 10⁸ L⁻¹ s⁻¹ was obtained when using DFUS at 20 kHz and 80 kHz. Although the yield of strong oxidizing substances from individual active bubbles decreased slightly, the significant increase in the number of active bubbles resulted in a higher synergistic effect. The combination of DFUS and PMS effectively promotes the generation of reactive free radicals and mass transfer processes, leading to efficient removal of tetracycline from wastewater. The study also found that the degradation rate of tetracycline was significantly influenced by factors such as initial pH, ultrasound power, and PMS dosage. The toxicity of tetracycline and its intermediates was assessed, and the results indicated that DFUS combined with PMS significantly reduces the toxicity of tetracycline. The mechanism of tetracycline degradation by DFUS and PMS was proposed, involving the generation of reactive oxygen species and the breakdown of tetracycline molecules through various chemical reactions. The study concludes that the combination of DFUS and PMS is a promising technology for the treatment of tetracycline in wastewater.This study investigates the degradation of tetracycline using dual-frequency ultrasound (DFUS) combined with peroxymonosulfate (PMS). The results show that DFUS significantly enhances tetracycline degradation compared to single-frequency ultrasound. The main reactive radicals involved in the degradation process are superoxide (O₂⁻•), sulfate radical (SO₄⁻•), and hydroxyl (•OH) radicals. The degradation pathways of tetracycline were identified, and the intermediates were found to be less toxic than the original compound. The number of active bubbles in the degradation vessel was calculated using a semi-empirical formula, and a higher value of 1.44 × 10⁸ L⁻¹ s⁻¹ was obtained when using DFUS at 20 kHz and 80 kHz. Although the yield of strong oxidizing substances from individual active bubbles decreased slightly, the significant increase in the number of active bubbles resulted in a higher synergistic effect. The combination of DFUS and PMS effectively promotes the generation of reactive free radicals and mass transfer processes, leading to efficient removal of tetracycline from wastewater. The study also found that the degradation rate of tetracycline was significantly influenced by factors such as initial pH, ultrasound power, and PMS dosage. The toxicity of tetracycline and its intermediates was assessed, and the results indicated that DFUS combined with PMS significantly reduces the toxicity of tetracycline. The mechanism of tetracycline degradation by DFUS and PMS was proposed, involving the generation of reactive oxygen species and the breakdown of tetracycline molecules through various chemical reactions. The study concludes that the combination of DFUS and PMS is a promising technology for the treatment of tetracycline in wastewater.