Abstract: Objectives Emerge the Finite element method into the DMB (Discrete-Module-Beam) method and improve the derivation of the lumped-mass stiffness matrix in order to efficiently apply the DMB method in complex and compound VLFS. Methods The 3D potential flow theory is first introduced in the DMB method to establish the hydroelastic equation. The finite element theory is then introduced to discretize each macro-submodule into micro beam elements and the lumped-mass matrix is derived based on the sub-structure approach and matrix manipulations. In dealing with complex boundary conditions, the cross-zeros-set-one approach or adding an additional constraint into the total stiffness matrix is adopted. In dealing with complex interconnections, the node numbering is first altered and then an additional constraint stiffness matrix is added into the total stiffness matrix. Results The DMB method is applied to VLFS with fixed/spring-damped boundary conditions and VLFS with hinged/rigid/spring-damped interconnections and good agreement is shown with results from the direct method. Conclusions The DMB method with the finite element theory is capable of analyzing hydroelasticity of VLFS in complex engineering scenarios in a fast and accurate way.