For the adequate strength, simple structure and easy manipulation, the radial gate is used widely in water conservation project.The radial gate is a kind of space frame structure which is calculated by the FEM and method of structure mechanics of planar system.Based on the classical shell theory,we analyzed the strong stiffened shell structure.Adopting the singular function, we determined the precise positions of girders and derived the static equilibrium equations and put forward the new method for calculating the sheet frame of the radial gate. The results by this method were compared with those by the finite element method and the planar system, problems of the feasibility and accuracy of this method can be discussed,and the feasibility and computation precision of the method are discussed.