Nuclear power as a green energy has attracted great interest, while the research of the lubricant materials of the moving components used in nuclear plants is insufficient. MoS₂ composite films, an excellent solid lubricant material, were irradiated by heavy ions to simulate the effects of neutron irradiation on the structure, mechanical and tribological properties. The structure analysis showed that the damage degree of heavy ions was proportional to the increased irradiation dose and energy. Irradiation destroyed the ordered arrangement of MoS₂ lattice, resulting in the amorphization of the composite film and the local formation of ordered MoS₂ nanocrystallines. The nanoindentation tests showed an increase in the hardness of composite films, which was associated with the distorted microstructure. Tribological experiments showed that irradiation led to the fluctuation of the friction coefficient and a significant increase in wear rate. The analysis of the counterpart showed that irradiation inhibited the transfer process of the wear debris and the formation of the transfer layer, leading to the degradation of the tribological properties. The post-thermal annealing of MoS₂ composite films after irradiation showed a self-healing behavior of MoS₂ lattice, suggesting a pathway of repair of irradiation damage. The pre-treatments of thermal annealing improved the crystallinity of MoS₂ composite films. Compare with as-deposited films, annealed films showed enhanced irradiation-tolerance, which was attributed to the more stable grain boundary and fewer internal defects. Tribological experiments showed the wear rates of annealed films were almost unaffected by irradiation, suggesting a new design strategy for lubricant materials used in irradiation environments.