Abstract: In the operation process of spallation neutron source injection system, the stripper foil is the key equipment to realize the conversion of negative hydrogen ions into proton injection. The nanometer to micrometer thick stripper foil is ultra-thin and fragile, and its installation and system vacuum attainment are much difficult, which is the focus of spallation neutron source research. This paper compares the present situation of the foils fixation with that of the foreign foils. The pressure distribution of the foil, as well as the pressure distribution of the diaphragm under different pressure difference between inlet and outlet, air disturbance around the foil and the system air flow, has been simulated by Fluent simulation. Finally, this paper gives a vacuum solution without sacrificing the stripper foil, which has obtained an ultrahigh vacuum environment for the system.