This study proposes a new synthetic test circuit (STC) for HVDC thyristor valve tests. The conventional STC with a 2-phase chopper requires a 3-phase transformer, a 3-phase diode rectifier, and an IGBT to facilitate the off state of an auxiliary thyristor. In the proposed STC, these three components are replaced with one diode and one resistor, which result in the simplified implementation of the hardware of the STC. Simulation and experimental results demonstrate the validity of the proposed scheme.