Grain boundaries (GBs) can serve as effective sinks for radiation-induced defects,thus notably influencing the service performance of materials.However,the effect of GB structures on the zero-dimensional defects induced by irradiation has not been fully elucidated.Here,the evolution of cascade collision in the single-crystal (SC),bicrystalline (BC),and twinned crystalline (TC) copper is studied by atomic simulations during irradiation.The spatial distributions of vacancies and interstitials are closely re-lated to the GB at a certain primary knock-on atom (PKA) energy.Compared with the TC,the BC displays a more obvious segregation of the interstitial atoms near GB,due to the characteristic of the greater interstitial binding energy.The evolution of Frenkel pairs is more sensitive to the change of the GB position in the BC.A more prominent defect annihilation rate is caused by the effect of the GB than that of the twin boundary(TB).The marked secondary emission phenomenon has been observed in the BC,which promotes the formation of an inverted pagoda-like defect distribution.There are similar sub-conical defect distributions and microstructures induced by cascade collision in the TC and the SC.It has been found that the influence range of the GB is wider in the BC.Meanwhile,the average flow stress of the irradiated copper is quantitatively calculated by establishing a physical strengthening model.The contribution of vacancy to the average flow stress in the irradiated BC and TC is obvious than that in the SC,due to the forma-tion of many vacancies.This study provides a theoretical basis for further understanding and customization of the metal-based equipment with good radiation resistance.