Direct current auto-transformer (DCAT) traction power supply system (TPSS) shows advantages in solving the rail potential and stray current issues. However, due to the high power level and high operation density in TPSS, it is difficult and costly to verify in the real urban rail transit system. Thus this paper proposes a novel DC traction system hardware emulator (DC-TSHE) for verifying the output performance of DCAT-TPSS by employing the static power electronics circuits. The configuration and operation principle are demonstrated firstly, and then the rail potential distribution laws of DCAT-TPSS are analyzed in detail. Moreover, the feasibility of the proposed DC-TSHE is also verified through simulation model and laboratory prototype. Both the simulation and experimental results verify the feasibility and effectiveness of the proposed DC-TSHE.