Abstract: In recent years, environmental pollution has become more and more serious. High concentration refractory organic wastewater is highly toxic and difficult to decompose. Therefore, developing a new high efficient wastewater treatment process is extremely urgent. Fe₃O₄/CeO₂ composite was synthesized using the co-precipitation method. The composite was used for the degradation of Orange G as Fenton-like heterogeneous catalyst. The process parameters were investigated by the single factor experiment. The degradation intermediate products were determined by TOF-MS/MS. The possible degradation pathway of OG by heterogeneous Fenton-like process was attained. The results indicated that the optimal conditions were pH value 2.0, H₂O₂ concentration 30 mmol/L, initial dye concentration 50 mg/L, catalyst dosage 2.0 g/L and temperature 30 ℃. Under the optimal conditions, the degradation percentage of OG was 96.2% within 120 min, and the TOC removal rate was 65.0%. Mass spectrometry analysis results showed that the OG degradation was mainly through three possible degradation pathways, including the process of azo bond rupture, desulfonation, hydroxylation and ring opening process. Eight possible degradation intermediate productions were measured, including aniline, phenol, naphthol and carboxylic acid.