In order to further improve the loss reduction effect of low-voltage distribution network, an auxiliary decision-making method of low-voltage distribution network loss reduction based on PI real-time database is proposed. Through PI real-time database, the line losses of three-phase line and neutral line in low-voltage distribution network are calculated, and it is judged that unbalanced load of neutral line can easily lead to large loss. Taking temperature as the main factor affecting the loss of low-voltage distribution network, by increasing the proportion of low-energy-consuming transformers, increasing the cross-sectional area of conductors and optimizing the operation mode of distribution network, the loss reduction decision of distribution network is completed. The test results in a trunk-type low-voltage distribution network in a city show that the proposed method can effectively improve the unbalanced load of distribution lines. Compared with the loss of each phase line and center line before loss reduction, the loss value after loss reduction shows a significant downward trend, and the bus loss rate of the proposed method is relatively low, all of which are controlled within 2%.