The beam of a laser cutting machine was taken as the research object, and ANSYS Design Explorer was used to optimize its structure. The stiffener size, wall thickness and rectangular hole of the beam of the laser cutting machine were taken as the main optimization parameters, and the beam was designed in a lightweight way on the premise that the original strength and stiffness of the beam remain were unchanged.The beam before and after optimization were used for workpiece cutting test respectively.The test results show that after optimization, the maximum deformation, stress and strain of the beam are decreased and their distributions are improved, the cutting quality of the cutting workpiece is improved and the weight of the beam is reduced by 10.5%