The invention discloses an irradiation-crosslinking heat-resistant modifier. The irradiation-crosslinking heat-resistant modifier is characterized in that the modifier is N-(fluorophenyl)maleimide with a functional group. The copolymer with two, three or more elements such as the N-(fluorophenyl)maleimide with the special functional group and FPMI is prepared; the polymer has good heat-resistant performance, can serve as the heat-resistant modifier of PVC, ABS and other ordinary plastic, can also serve as the heat-resistant modifier of PA, PPO and other engineering plastic and has a good effect. Though the heat-resistant temperature of PA, PPO and the like can be raised through a copolymer with two elements such as N-phenylmaleimide/maleic anhydride and CPMI-KH550-St reported in the patentCN 104356297A and the patent CN 107474185B, the heat-resistant performance can be better improved when the same mass parts are applied.