Abstract: To address the issue of identifying the causes of abnormal line loss rates in low-voltage transformer district, a new line loss rate analysis method based on statistical and technical deviations was proposed. Firstly, combined with MATLAB numerical simulation, the ideal line loss rate was introduced by analyzing the statistical line loss rate and theoretical line loss calculation model. On this basis, the relationship among statistical line loss rate, theoretical line loss rate and ideal line loss rate was compared and analyzed to obtain the indexes of statistical and technical deviations. Then by comparing the deviation index with the threshold, the cause of abnormal line loss rate can be determined and corresponding loss reduction measures can be formulated. Finally, engineering practice has confirmed the effectiveness of this scheme in identifying the causes of abnormal line loss rates. After implementing appropriate technical loss reduction measures, the technical deviation index of the transformer district decreased from 1.2 to 1.0, and the line loss rate decreased from 3.1% to 2.5% under the same power supply.