The utility model discloses a circuit for detecting a current signal. The circuit includes a current reference circuit (1), an operational amplifier integrated chip N1 and an output circuit (2). One comparing input terminal of the operational amplifying integrated chip N1 is used for the input of voltage values of current values of a, b and c phases. The other comparing input terminal of the operational amplifier integrated chip N1 is connected to the current reference circuit (1). An input terminal of the output circuit(2) is connected to an output terminal of the operational amplifier integrated chip N1. An output terminal of the output circuit(2) is an output terminal of the circuit for detecting the current signal. The circuit provided by the invention is accurate in detection and low in power consumption.