An impedance matching method for a CLC branch of a low-frequency resonance suppression device is provided, which includes: establishing an equivalent circuit model for a power supply system with a low-frequency resonance suppression device joined in; obtaining, according to a target low-frequency harmonic frequency band and the equivalent circuit model, a constraint required by the power supply system for suppressing low-frequency harmonics; constructing an objective function based on a low-frequency harmonic suppression rate in a bus of the power supply system; obtaining a multi-constraint objective optimization function of CLC branch impedance based on the constraint and the objective function; and solving the multi-constraint objective optimization function through an improved harmony search algorithm to obtain an impedance parameter of the CLC branch. The present disclosure can ensure a low-frequency harmonic suppression effect for the power supply system.