The invention relates to the electrical test field of high-voltage DC power transmission converter valves, and discloses a voltage source for a service test of a high-voltage DC power transmission thyristor valve. The voltage source comprises a transformer and an auxiliary main circuit. The voltage source is characterized in that a controllable rectifier bridge is arranged between the transformerand the auxiliary main circuit, a voltage sensor is arranged at an output terminal of the auxiliary main circuit, and the voltage sensor is connected with a negative feedback network to control the controllable rectifier bridge.