Abstract: Processing and doping are important methods in the engineering application and development of graphene. Ion irradiation technology is an important approach to realize the processing and doping. The molecular dynamics model of graphene irradiated by Silicon neutral and the tensile model of defective graphene after irradiation damage are established. The defect types and quantities in graphene under different irradiation conditions, including ion dose, energy and angle, are analyzed and the tensile behaviors of defective graphene caused by different incident numbers of Si ions are also investigated. The conclusions are as follows:When the ion energy is small, incident particles will be adsorbed on the surface of graphene; with the increase of ion energy, incident particles can penetrate the target and form some defects; when the ion energy reaches a certain large value, there is no adsorbed atom. With the increase of the ion dose, the numbers of sputtering atoms and defects increase and the main defect is vacancy. The tensile mechanical properties of the corresponding defective graphene, such as tensile strength and limit strain, reduced with the increase of the defects number. The tensile failure mechanisms of the defective graphene caused by irradiation and the pristine graphene are different. The strengthened stage in the tensile curve of the former is shorter and the location of fracture initiation and the fault strike are dominated by the defect cluster.