The paper intends to analyze quantitatively the correlation between the NASTRAN finite element (FE) model and a testing model for a middle raft frame of a floatingraft isolation system. The first five vibration modes of the raft frame are estimated by finite element method (FEM) and measured by testing. The modal assurance criterion (MAC) matrix is established in LMS virtual lab for relativity analysis between the FE model and the testing model. The MAC estimated by LMS virtual lab shows that the modal computed by FEM is basically correct and the method can be used for dynamic esponse analysis of the structure.