A circuit for three-phase detection, a method for three-phase detection and a compressor are provided. The circuit for three-phase detection includes a first optical coupler and a second optical coupler. A first input end and a second input end of the first optical coupler are respectively connected to a first phase wire and a third phase wire of a power supply assembly, and a first output end of the first optical coupler provides a first output signal. A first input end and a second input end of the second optical coupler are respectively connected to a second phase wire and the third phase wire of the power supply assembly, and a first output end of the second optical coupler provides a second output signal. The first output signal and the second output signal are used to indicate a phase state of a three-phase alternating current of the power supply assembly.