Abstract: In order to investigate the changes of structure and mechanical properties of silicon carbide irradiated by high energy ions, the 4H-SiC after 122 MeV ²⁰Ne⁴⁺ ion gradient multi-dose irradiation was investigated by Raman spectrum and nano indentation technology. The Relative Raman Intensity of the sample decreases exponentially with the increase of dose, and there are scattering peaks representing disordered Si-C bond and homonuclear Si-Si bond. Preliminary fitting based on the DI/DS model shows that the expansion of defect clusters in the low dose range is the main factor causing the disorder, while the disorder in the high dose range is caused by amorphization in the process of direct ion collision and extended defect clusters. The hardness of irradiated silicon carbide is the joint action between dislocation pinning and covalent bond breaking. Between 0~4.00 dpa, the hardness increases with the increase of dose, and between 4.00~8.05 dpa, the hardness decreases with the increase of dose. At 8.05 dpa, the hardness is slightly higher than that unirradiated area. At the same time, the covalent bond breaking and dislocation pinning reach equilibrium.