A circuit and a method for reducing interference of power on/off to hardware test. The circuit includes: a power unit, a voltage processing unit, a PSU and a to-be-tested hardware. An input terminal of the voltage processing unit is connected to the power unit, an output terminal of the voltage processing unit is connected to an input terminal of the PSU, and an output terminal of the PSU is connected to the to-be-tested hardware; the power unit is configured to provide an operating voltage; the voltage processing unit is configured to eliminate electric sparks caused by instability of the operating voltage at an instant of power on/off; the PSU is configured to convert a stable operating voltage outputted from the voltage processing unit into a direct current voltage required for the to-be-tested hardware; and the to-be-tested hardware is configured to receive the direct current voltage outputted from the PSU.