In view of the fact that the noise of power capacitor devices in conventional high voltage direct current (HVDC) transmission projects is prominent and needs to be controlled from the source, test circuits for noise test in accordance with the actual operating conditions of power capacitor units are proposed, including a bridge circuit which can load power frequency and multiple harmonic currents simultaneously, and a test circuit which can load DC voltage and multiple harmonic currents simultaneously. Meanwhile, the technical scheme of the harmonic power supply, which is the key equipment in the circuit, is illustrated. The feasibility of the circuits are verified by the simulation waveform. Based on the proposed circuit, a power capacitor noise test platform is set up, and the noise test of multiple power capacitor units in converter station are carried out. The comparison between the test results and the theoretical values proves that the test circuit can meet the noise test requirements of power capacitor units in HVDC projects.