Abstract: Compared with quasi-static and pseudo-dynamic tests, the hybrid simulation usually has more complex boundary conditions (BCs) of experimental substructure (ES). Limited by the laboratory loading conditions, the BCs of the substructure are often difficult to fully realized, which may have a great impact on the fidelity of hybrid simulation, that is, the problem of incomplete BCs in hybrid simulation. To solve the problem of incomplete BCs, a novel testing method is proposed. Two numerical modules of the ES are established in this method and are used to correct the incomplete restoring force of the ES. The difference between the two modules sets the same BCs as the ES, which is incomplete BCs. In this study, the influence of coupling degree of boundary DOFs and numerical module error on the accuracy of this method is analyzed, and it is verified that this method has good robustness to the numerical modules with model error. Finally, the seismic performance of a two-story and two-span moment-resisting frame structure is numerically analyzed using the proposed method. Compared with the conventional hybrid simulation and weakly coupled hybrid simulation method, the results show that this method has the ability to solve the problem of incomplete BCs and has higher simulation accuracy.