2-Methyl-4-chlorophenoxyacetic acid (MCPA) is a herbicide that poses a threat to the environment. In this study, MIL-88A was utilized as a photocatalyst to degrade MCPA. Results demonstrated that the Light/MIL-88A/H2O2 system exhibited remarkable photo-Fenton catalytic activity. Under optimal conditions of pH = 3.8, H2O2 concentration of 1.2 mL/L, MIL-88A dosage of 0.2 g/L and an initial MCPA solution concentration of 50 mg/L, the degradation efficiency reached its peak, achieving a 99.9 % degradation rate of MCPA within 60 min. The morphology, structure, and photocatalytic performance of MIL-88A were investigated using characterization techniques such as SEM, XRD, XPS, and UV–vis DRS. Free radical quenching experiments and ESR characterization demonstrated that the main active material in the degradation of MCPA was •OH. The possible degradation pathways of MCPA were hypothesized by combining the results of Gaussian software and LC-MS analysis. Furthermore, the toxicity of MCPA was evaluated using T.E.S.T. software and mung bean germination experiments. The results revealed that the degradation of MCPA by Light/MIL-88A/H2O2 system could achieve solution detoxification.