A circuit for sampling current includes a current transformer, a reset resistor, a diode, a sampling switch, and a current sampling resistor. The current transformer includes a primary winding and a secondary winding. The reset resistor and two ends of the secondary winding are connected in parallel. The sampling switch, the diode, and the current sampling resistor are connected in series and then connected to two ends of the reset resistor in parallel. The primary winding is for connecting to a circuit to be sampled. When a current flows through the primary winding and the circuit to be sampled and the sampling switch is turned on at a negative AC half cycle, the circuit for sampling current samples the current flowing through the circuit to be sampled.