This paper presents an access to modeling riveted and welded truss-joints on carrying structure with spatial lattice girder design. The paper illustrates the real model (geometric model) of the most loaded truss-joint on specific carrying structure with its overall complexity. It also illustrates the mathematical model (FE model) of the truss-joint in two designs introducing simplicity, in order to analyze the truss-joint by using a computer and an appropriate software package. FE models (the finite element models) keep up all the characteristics of the geometrical model of the truss-joint, ushering in suitable methodology for this purpose. The need for modeling truss- joints imposes itself as a prior step to further local analysis of stress-deformed conditions of the joint-steel plate under the influence of outside loads. The parallel modeling of the same truss-joint in two constructive designs enables further comparative analysis of stress-deformed shape under same loads and summarize more appropriate constructive design of the truss-joint and emphasizes the need for its optimization.