In recent years, China’s economy and technology have achieved rapid development, and the demand for gantry cranes has also increased year by year. This paper mainly analyzes the main beam of the gantry crane and builds on the basis of the optimization principle. The three-dimensional model of the gantry crane has been optimized to reduce the weight of the main beam of the gantry crane. Under the premise of ensuring that the rigidity and strength of the main beam meet the requirements of use, the size of the main beam is reduced, which not only saves effectively. The raw materials are also easy to assemble and repair.