The neutral line is one of the components of the whole distribution transformation system. In the 400v low-voltage distribution network, the neutral point, that is, the neutral line, will be directly grounded to form an equal potential with the earth. Without potential difference, the neutral line will naturally not be charged and be in a safe state. Based on wireless communication technology, this paper develops a neutral line live detection device for 400v low-voltage distribution network. Using the transmission of 4G mobile communication network, the embedded fault detection software of wireless acquisition unit is designed based on single-chip SOC chip to complete the data acquisition and wireless transmission of current transformer. Aiming at 400v low-voltage distribution network, the live location criterion based on zero-sequence current mutation is used to locate the neutral line. The research results show that the maximum accuracy of the proposed method is 96.04% and the average is 88.58%. It shows that the proposed neutral line live detection method for power equipment is extremely effective. The validity of the detection device in this paper is proved.