Abstract: Using Kantorovich Method, the tube structures with Complicated plane shape are analyzed in this paper. According to the spare thin-walled structure theory, the displacement trial functions are given by taking the "shear lag effect" into account. Then, the Euler's differential equations as well as natural boundary. condition are established with the help of variational method. The homogeneous solution of the differential equation system is solved by using matrix notations. An example is given at last. This method can be used in primary design.