The cantilever is the key part of a jack-up drilling unit. Its strength is the key to measure the drilling ability and safety performance of a jack-up drilling unit. Take a 400 ft jack-up drilling unit as an example, the article introduced the test conditions, test procedures and the combination of test load when the cantilever under load condition. At the same time, use the finite element analysis software to calculate the structure strength and contrast the theoretical calculation of deformation with test measure data, which shows the good consistency. It provides a strong guidance for the cantilever load test method and deformation analysis.