This paper proposes a extend linear equivalent method that can extend the linear equivalent micropolar beam model to the nonlinear equivalent micropolar beam model to analyze nonlinear vibration for large space truss structure, and also proposes a lattice enhancement method to improve the cantilever truss for the buckling problem that exists in space cantilever truss structures. The nonlinear equivalent model is obtained by introducing a corotating coordinate system into the linear equivalent beam model. Since the instability of the fixed root end of the cantilever truss is the main reason for buckling, the method of strengthening the longeron of the truss lattice by lattice is proposed. The accuracy of the equivalent geometric nonlinear model and the effectiveness of the improved cantilever truss structure are verified by four numerical simulation examples. The methods proposed in this paper provide some reference for studying the dynamics analysis of large space trusses and the design of structures.