Abstract: Using UV-LED / Cl₂ Advanced Oxidation Process to study the degradation of metoprolol (MTP), one of the β-blocker, the effects of light intensity, chlorine dosage, pH, TBA and other factors on the degradation of MTP are investigated. Studies have shown that UV-LED / Cl₂ can effectively remove MTP by synergy. The MTP degradation during UV-LED / Cl₂ treatment satisfies pseudo-first-order kinetics, and the pseudo-first-order rate constants of MTP (k_obs) increases with the UV-LED light intensity and the pH of the solution. With the increase of the chlorine dose, the k_obs of MTP increases first and then decreases. The k_obs of MTP decreases with the increase of the initial concentration of MTP and TBA, and TBA has a strong inhibitory effect on MTP degradation during UV-LED / Cl₂ treatment.