Abstract: The functional development was carried out on an existing X-ray photoelectron spectrometer. The developed space alternating temperature atomic oxygen (AO) irradiation device was integrated into the fast sampling chamber without changing the operating principle and the existing functions. In-situ characterization of materials under the simulated space alternating temperature AO irradiation was realized through solving the problems of cluster structure matching and performance compatibility. The AO flux of space alternating temperature atomic oxygenirradiation device was measured using the method of mass loss of Kapton. All the oxygen flux, bias pressure and microwave current have great effects on the AO flux. The system test showed that the structure and composition of WS₂ film were changed greatly by the AO irradiation, and the difference in chemical composition and structure caused by the AO irradiation at different temperature were not negligible.