Abstract: In order to expand the stability of substructure testing to nonlinear structures, the unconditional stable energy-conserving time integration algorithm is implemented in the substructure test, and a substructure testing method based on the algorithm, called energy-conserving substructure testing method, is developed. The equivalent force control method is used to solve implicit difference equation in the testing method. The computation of module CR is presented in the block diagram of test, which solves the key problem in the implementation of energy-conserving time integration algorithm in substructure tests. Then numerical simulations of energy-conserving substructure tests of SDOF linear and nonlinear structures were carried out. The results validate the feasibility of energy-conserving substructure testing method. Finally energy-conserving substructure pseudodynamic tests were conducted with linear spring and nonlinear buckling-restrained brace specimen respectively. The results show that the energy-conserving substructure testing method is applicable for both linear and nonlinear structures.