The invention discloses a method for simulating irradiation damage of a nanostructure nuclear material based on hybrid LKMC and OKMC. The method comprises the following steps of establishing an eventrate table of an OKMC area; determining the radius of an LKMC area for a given interface; establishing mapping between LKMC grid points and defect states; establishing a transition rate table among different defect states in the LKMC area; expanding and calculating a model inner rate table; establishing a rate table of an OKMC and LKMC transition area, and conducting rate processing; establishinga defect cluster event rate table of the LKMC area, and conducting rate processing; for events of different areas, calling the corresponding rates, and selecting and executing the events. According tothe method, through a method of hybridizing LKMC and OKMC, a calculation method with different resolutions for defect properties is adopted in different areas of a grain boundary, and the defect behaviors of complex interface structures can be accurately simulated; compared with existing simulation methods, the simulation precision and the simulated time and space scale are taken into account, and the difficulty of extracting function parameters under the function of the coarse-grained modelling defect-grain boundary is lowered.