Abstract: To ensure the realization of real-time substructure test, based on the concept of gain margin, a stability analysis method that can consider the influence of the comprehensive factors of real-time dynamic substructuring (RTDS) system was proposed. The coupling effect of numerical integration algorithm and loading system on the stability of real-time substructure test system was studied. The analysis results show that the numerical integration algorithm may enhance or reduce the stability of RTDS system in different cases. Moreover, the deficiency of the simplified model used to analyze the dynamic characteristics of the loading system is improved by this stability analysis method.