Abstract: A new-type of outer combined plasma photolysis (OCPP) technology was designed and constructed.The technology simultaneously produced plasma and KrI^* excimer UV radiation with a high-pressure power supply. Simulated waste gas containing styrene was decomposed with the OCPP technology. The results showed that the styrene removal efficiency was up to 84.4% in OCPP (Kr 26.60 kPa, I₂ 6 mg), while the removal efficiency, energy yield were increased by 20.6%, 5.7 g/(kW·h), respectively,in contrast to dielectric barrier discharge (DBD) plasma, when the applied voltage, gas flow rate, and initial mass concentration of styrene were set at 9.0 kV, 3.26 m³/h, and 1,265 mg/m³, respectively. Moreover, the factors influencing styrene decomposition were investigated, including pressure of filled Kr and mass of I₂, quartz material, gas flow rate, initial mass concentration of styrene, as well as reactor configuration. Lastly, the solid depositions on the internal wall of the OCPP were analyzed by a Fourier Transformation Infrared Spectrometer (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS), on the basisof which, the likely reaction mechanisms for the removal of styrene by OCPP were discussed.