A grounding detection apparatus, a control method thereof and a pool system are provided. The grounding detection apparatus includes a detection circuit, which includes a live line connection terminal, a neutral line connection terminal, a grounding terminal, a first impedance circuit, a sampling resistance, a differential amplifying circuit and a comparison unit; a first terminal of the first impedance circuit is connected with the live line connection terminal; a second terminal of the first impedance circuit is connected with a first terminal of the sampling resistance and a first input terminal of the differential amplifying circuit; the sampling resistance is configured to convert a sampling current to a sampling voltage; the differential amplifying circuit is configured to amplify the sampling voltage to form an amplified sampling voltage; and the comparison unit is configured to compare a threshold voltage and the amplified sampling voltage and output a comparison result.