Abstract: In electron beam processing equipment,the focusing system and deflection system are the key factors in determining the excellent performance of the electron gun. This paper introduces the principle and characteristics of electron beam focusing and deflection technology and summarizes the research progress made in the optimization results of electromagnetic lens structure,electron beam focusing law,and controlling the reduction of beam spot aberration. The shortcomings of the current electromagnetic lens-controlled electron beam processing are analyzed,and the future development trend of electron guns is prospected.