Abstract: In order to coordinate substructures with distinct physics in a hybrid test framework, this paper utilizes the interface element method to build up the overall stiffness matrix based on the general variational principle, where the statically condensed boundary stiffness matrices of substructures and the stiffness of interface elements are combined. This strategy makes the hybrid test more flexible particularly facing the substructures with different element types and meshes. Meanwhile, a transfer function was introduced to the method to correlate the subdomains with different numbers of degrees of freedom. Finally, the nonlinear time history analysis was conducted on the shell-beam model, which fully demonstrates the feasibility and the accuracy of the interface element method.