Abstract: Multiweb structures are integral ones composed by upper skin,lower skin and webs. This kind of structure can reduce the height and weight of wings and at the same time,maintain the strength and rigidity. Moreover,the application of composite multiweb structures in modern fighters is becoming an inevitable trend because of the various advantages of this material. To solve the problem of buckling,the theory of nonlinear stability of composite laminates and method of rigidity equivalence are adopted in this article. The relevant constitutive equation and nonlinear stability governing equations are established. At last,the nonlinear equations are solved by numerical computation. The overall and local critical loads of buckling are obtained under various boundary conditions and compressive and shear loads in plane. The validity and effectiveness of the theory and method are demonstrated by comparison with the solutions obtained by the other existent references. They can satisfy absolutely the demands of engineering.