Abstract: With the advantages of low cost, short construction period and relatively small foundation disturbance, tubular foundation has become one of the important foundation forms of offshore wind power in China. Because of its complex foundation structure, the classical foundation calculation method can not accurately evaluate the vertical bearing capacity of its foundation. In this paper, the lower bound method of finite element limit analysis is used to transform the tube soil interaction into an inequality constraint condition between the tube soil friction and the undrained shear strength of the soil, and a lower bound solution program for the vertical bearing capacity of the tube foundation is established. On this basis, the effects of soil strength non-uniformity, the length diameter ratio of the barrel foundation and the friction between the outer wall of the barrel and the soil on the vertical bearing capacity of the barrel foundation are analyzed, and a formula for calculating the vertical bearing capacity of the barrel foundation considering the above factors is proposed.