Crosslinked ethylene-vinyl acetate copolymer/montmorillonite (EVA/MMT) nano-composite was prepared by UV irradiation. Effect of MMT on gel content of crosslinked EVA was analyzed. Other factors, such as time, temperature and atmosphere of the irradiation and thickness of the samples were studied. The results show that MMT could promote the crosslinking reaction, with the optimal conditions of 100℃ irradiation of 2 min, where the gel content could be 95%. Irradiation atmosphere and samples thickness affected the gel content notably at beginning of the irradiation, but they became less effective on the gel content after 2 min of irradiation.