Abstract: The composition of passivated film phase on the surface of 304 stainless steel was tested by X-ray diffraction, and the Monatomic and Gas Cluster Ion Source in the X-ray photoelectron spectroscopy were etched on the surface of 304 stainless steel at different voltages and different times.The influence of voltage and time on the surface element combination state of 304 stainless steel was analyzed. At the same time, the depth analysis method was used to detect the element distribution perpendicular to the depth of the passivation film on the surface of the sample. The results show that the outer layer of the passivation film is iron oxide and the inner layer is chromium oxide.The thickness of the passivation film is about 120 nm.