The work aims to improve the corrosion resistance of CrFeCoNiMo0.2 high entropy alloy. The surface of non-equiatomic CrFeCoNiMo0.2 high entropy alloy (HEA) was irradiated by high-current pulsed electron beam (HCPEB). Microstructure and corrosion resistance of the CrFeCoNiMo0.2 HEA before and after high-current pulsed electron beam (HCPEB) irradiation were studied systematically. The microstructure evolution and corrosion morphology of the irradiated surface were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Corrosion resistance of alloy before and after HCPEB irradiation was studied by CHI760C electrochemical workstation in 3.5 wt.% NaCl solution. The results of XRD analysis indicated that the surface of the irradiated sample exhibited preferential orientation on (200) crystal plane. Microstructure observations revealed that caters and a compact remelted layer with a thickness of about 3~5 μm were formed on the surface of the alloy after HCPEB irradiation. The density and size of craters formed on the irradiated surface were significantly decreased with the increasing number of pulses. Besides, the HCPEB treatment eliminated porosity and composition segregation of the sintered alloy, thereby achieving homogeneity of structure and composition. The potentiodynamic polarization curves demonstrated that all the irradiated samples had a positive potential and a lower current density in 3.5% NaCl solution compared with the initial sample. The results of Nyquist and Bode plots showed that the surface of the irradiated samples had better capacitive behavior and corrosion resistance, among which 30-pulsed samples possessed the best corrosion resistance. HCPEB irradiation eliminates the structural defects on the surface of sintered alloy, promotes the more uniform distribution of surface elements, and further improves the corrosion resistance of CrFeCoNiMo0.2 high entropy alloy.