Problems of huge amount of elements and time consuming in computation often occur in finite element modeling of complicated structures. Limited modal test data can only be obtained due to testing restrictions, for instance, limited test points and lack of test time during maintenance or overhauling. In this paper, a pseudo mode shape method was proposed to provide adequate spatial models (i.e., mass, damping, and stiffness matrices) to cover more frequency range of frequency response functions of substructures. These substructures can be assembled with mother structures to reveal the vibration response of the complete structures in the frequency ranges. A 2-D beam structure is used to demonstrate the validation of this method.