The base of Parallel loading device withstand the pressure of hundreds of tons, Limited by the conditions of use, All components of the device must be manual handling, so Its weight becomes very sensitive. The initial design weight of base are about 170 kg, By handling environmental constraints, four men lift is also very convenient, Therefore it's urgent to reduce weight. In this paper, a powerful modeling capabilities of UG combined ANSYS topology optimization module on the base for a topology optimization, We refer to the shape of topology optimization design of the final design of the structure. Through finite element analysis, the structural stiffness and strength to meet the design requirements, And weight decreased from about 170 kg to 120 kg, reduced by nearly 30%.