The work aims to study the effects of high current pulsed electron beam (HCPEB) on microstructure and corrosion resistance of 50BA steel surface. Surface treatment was carried out to 50BA steel for different pulse times, organizational change was observed with a scanning electron microscope, and in 3.5wt% NaCl solution prepared using NaCl and deionized water (room temperature) for dynamic polarization measurement. After HCPEB treatment, grains on the surface of 50BA steel specimen were refined, and a fine and uniformly distributed acicular martensite was produced. With the increase of pulse number, the surface tended to be smooth. Self-corrosion potential of sample surface increased from ?0.660 V to ?0.629 V while the corrosion current decreased from 1.48×10?6 A to 8.36×10?7 A. With the increase of pulse number, the corrosion potential increased while corrosion current on the sample surface, corrosion rate and corrosion tendency decreased, the corrosion resistance of the specimen surface was best after 50 times of pulse treatment. After HCPEB treatment, the surface microstructure is subject to phase transition, the surface smoothness and presence of uniform fine acicular martensite theoretically account for corrosion resistance improvement of 50BA steel. In order to improve the corrosion resistance of 50BA steel, pulse number should be controlled over 30 times, and the higher, the better.