In order to better complete the field inspection function of smart meter, the detection method of high impedance fault (HIF) is optimized and implemented. The proposed method uses smart watt-hour meters as sensors for HIF detection in distribution network system, instead of installing separate sensors. Based on the even harmonics in the voltage waveform measurement data, each smart watt-hour meter calculates an exponent to measure the even harmonics in the voltage waveform. If the index calculated by any smart watt-hour meter continues to exceed the threshold for a specified period of time, the fault will be detected. Three scenarios are tested with the experimental device, and the results show the effectiveness of the proposed method. Compared with the detection methods based on wavelet and harmonic, the proposed method has obvious advantages in detecting power electronic loads.