Abstract: Radiation-induced crosslinking mechanism of poly (vinylidene fluoride) and characterization of the crosslinking density by XPS have been first studied. The calculated β value of poly (vinylidene fluoride). is 0.7. It is found that the radiation-induced crosslinking of poly (vinylidene fluoride) is in agreement with the general expression, in which the sol fraction is telated to radiation dose^[1]. The dose of gelation of poly(vinylidene fluoride) obtained by XPS is 1.59 mrad.