The formation mechanism of contact resistance between bipolar plate and gas diffusion layer is studied. The factors affecting the contact resistance are analyzed，e.g.，temperature，load，and roughness. A mathematical model is established and used to predict the values and variation rule of the contact resistance by means of a simulation tool. Tests are carried out on the interface contact resistance of the metallic bipolar plate and carbon paper layer for verification. It is shown that the calculated results agree well with the test data.