Lifting hook is an important bearing part of hoisting machinery. Its mechanical performance and safety are directly related to the safety of life and property of operators, and the ultimate bearing capacity is a key index. A new type of single chip lifting hook has been developed by domestic crane manufacturers to replace foreign similar products. Its rated lifting capacity is 45 t, and its length along the force direction is 1.398 m at work. According to the new type of single lifting hook and double lifting hook assembly developed by the enterprise, the ultimate bearing capacity of the lifting hook assembly is tested, which provides the technical basis for determining the material and production process of the lifting hook.