UV-Fenton process was applied to oxidize the unsymmetrialdimethy hydrazine(UDMH) wastewater. The optimal manufacturing process and the primary factors contribute to the UV-Fenton oxidation were determined by orthogonal experiments with removal efficiencies of the UDMH and COD in wastewater as two main monitor index，and the removal efficiencies of UDMH wastewater of five kinds of reaction systems were compared. Results show that when initial H₂O₂ is 1.5 times of the theoretical quantity(1.5 Qth)，the molar ratio of Fe²⁺ to H₂O₂ is 1：10，pH value is 3.5，room temperature is 25 ℃，and the reaction time is 45 min，the removal effciency of UDMH and COD is over 99% and 95.8% respectively. The change curves of degradation intermediate products CN- and HCHO and the UV-visible spectroelectrochemistry spectra of UDMH wastewater degradation processes were studied. Results show that UV-Fenton process is efficient in UDMH wastewater treatment.