A detection device, an inverter, and a detection method are disclosed. The detection device is configured to detect a leakage current flowing through a conductor. The detection device includes a magnetic core, a detection winding and a calibration winding both wound on the magnetic core, a detection circuit, and a calibration circuit. The detection circuit is coupled to the detection winding, and configured to sample a detection signal of the detection winding to obtain a leakage current detection value. The calibration circuit is coupled to the calibration winding, and configured to provide a calibration signal to the calibration winding.