Fe/ZSM-5 catalyst was prepared with ZSM-5 molecular sieve as support and Fe(NO3)3·9H2O as Fe source. The heterogeneous Fenton system composed of Fe/ZSM-5 and H,0, was used to de-grade methyl orange. The effects of H2O2 dosage, catalyst dosage, pH value , reaction temperature andtime on the degradation of methyl orange were studied. The results showed that the degradation rate ofmethyl orange could reach 93.8% under the optimal conditions of 1. 6 g catalyst, 0. 3 mol/L H,O,, pH 3, 30℃and 60 min.