Arc fault is an important cause of the electrical fire, aiming at the malfunction and rejection of fault arc protection algorithm under nonlinear load conditions, a series arc fault detection method based on current similarity and high-frequency energy is proposed. Refer to the standard, building an arc fault experimental platform and conducting experiments. Analyze the arc current characteristics from the perspective of time domain and frequency domain. The wavelet function is used to preprocess the current signal, and the characteristic quantities of low and high frequencies are selected. The arc fault characteristic quantity threshold is set, and the arc fault identification algorithm is proposed on this basis. Experimental results show that the algorithm can accurately identify the arc fault under various load conditions, and there is no malfunction and rejection action.