A circuit and method for realizing a combined connection of neutral wires or live wires using phase information of the neutral wires and the live wires are provided. The circuit includes a phase detection module. The phase detection module is connected to a power grid via the live wire VL and the neutral wire VN. The phase detection module includes a high-voltage phase detector, a first inverter and a second inverter. The output of the high-voltage phase detector is sequentially connected to the first inverter and the second inverter. The method includes: arranging nodes on the live wire VL and the neutral wire VN of the power grid, respectively; defining the nodes by determining a phase relationship that a high-voltage signal first appears on the live wire VL or the neutral wire VN; and connecting systems to be connected in parallel to the power grid through the nodes.