The performance of the current transformer used for watt-hour meter directly affects the meter's measurement accuracy. In view of the issues existing in the present electromagnetic current transformer such as easy to saturation， smaller measurement range， etc， a design plan of multi-function watt-hour meter based on PCB electronic current transformer is proposed. First， the structure and principle of a PCB air core coil sensing unit are analyzed， the interface circuit between the air core coil sensing unit and the measurement IC is designed， and the test data show that the transformer has a good performance. Then， the meter's hardware is elaborated which uses the three-phase high-precision measurement IC ADE7758 and high-performance， low power-loss H8 microcontroller as the core. Based on this， the main idea of meter's software is briefly described. The meter with high measurement accuracy and low power-loss has good prospects for practical application.