Abstract: In order to reduce the post-earthquake damage of modular steel structures, a modular steel structure system with distributed friction energy dissipation connections and its vertical connection joint is proposed. A single-span, 2-story, 1/2-scale steel frame specimen was designed. Through quasi-static test, the failure mode, hysteretic curve and skeleton curve of the specimen were obtained, and its ductility, energy dissipation capacity, strength degradation and stiffness degradation curve, steel strand stress level change were analyzed. A refined finite element(FE) model was developed using ABAQUS for parametric analysis. A simplified simulation method of joints in the FE analysis was proposed and validated, and an elastoplastic time-history analysis of the overall structure was carried out. The results show that the specimen exhibits excellent seismic performance, with an average ductility coefficient of 3.93 and an equivalent viscous damping coefficient of 0.29. The FE simulation results agree well with the experimental results. Parametric analysis results show that the cumulative energy dissipation of the structure is positively correlated with the initial tension of the steel strand, the friction coefficient of the sliding surface and the maximum allowable slip. Engineering cases analysis indicates that the friction joints remain in an elastic state without sliding under the frequent earthquake. The joint sliding friction energy dissipation under the rare earthquake can provide an additional damping ratio of approximately 3.9% for the structure, effectively enhance the overall energy dissipation capacity of the structure and reduce the plastic damage of the main components.