Abstract: This study aims to improve the accuracy and adaptability of fault detection in distribution networks. In response to the limitations of traditional fixed threshold methods in complex working conditions, an adaptive fault identification path based on power frequency signal setting without setting technology is explored. Taking common faults in the distribution network as the research object, a dynamic criterion construction method based on real-time working conditions was designed by deeply analyzing the characteristics of phase to phase short circuits and single-phase grounding faults. A comprehensive application scheme was proposed, including feature extraction algorithm, no setting criterion design, and multi-level detection logic. The research results indicate that this technology can effectively cope with load fluctuations and network topology changes, achieve fast and accurate identification of fault types in different operating environments, significantly improve the sensitivity and reliability of detection, and provide innovative support and technical guarantee for the intelligent operation of distribution networks.