Abstract: Outgassing of polymer materials induced by proton radiation can cause the molecular contamination. According to the hypothesis occurring in the proton radiation process on polymer materials,based on the diffusion theory,simulation of mass loss induced by proton radiation for polymer materials was researched. The mathematical function between mass of volatile in the material and radiation time was obtained using the variable separation approach. Mass loss for the polyimide (PI)film obtained from experiments and parameters in the model was calculated through curve fitting in order to validate the applicability of the model. The results showed that the maximum error between the model of mass loss and experiment was-5.8% and the model of mass loss was applicable to PI film and can be used for prediction on mass loss of polymer materials induced by proton radiation.