Elastic-plastic analysis of timber frame and its seven strengthened projects are analyzed with the software ANSYS10.0. The numerical calculation and material mechanics calculation for the timber beam are compared to verify the correctness of the finite element model. The paper also analyzes the law of stress and strain of timber beam. In contrast with the yield load and ultimate load of strengthened timber frames, it shows that the lateral resistance of timber frame with corner supports is greatly improved. And a strengthened project for the timber frame is put forward.