The large increment method(LIM) is an iterative method based on the force method and the generalized inverse matrix theory. In the nonlinear initial application of trusses and rigid frames, LIM reaches the same solution as the displacement-based finite element method with the same number of iterations or even less. Aiming at the complex bar structure, we discussed the application of LIM and contragradient law to the complex frame structure, established the LIM basic formula in frame structure and proposed the analysis approaches for complex boundary condition and composite joints. The illustrative example of linear elastic problem clearly reveals that the accuracy and the efficiency of LIM are the same as those of displacement-based finite element method. The method is also applicable to elasto-plastic problems without considering the plasticity of the support itself, which lays the foundation for LIM in the elasto-plastic analysis of complex bar structures.