The invention discloses a QRNN-based reasonable range estimation method for low-voltage transformer area line loss rate in the technical field of line loss rates. The method aims to solve the technical problem that in the prior art, the line loss rate evaluation basis cannot reflect the difference of a transformer area in structure, power supply range and load level, and comprises the steps of collecting transformer area operation data based on an existing power utilization management system, and screening out transformer area line loss rate influence factors; correlation analysis is carried out on the line loss rate of the transformer area, and line loss rate key factors influencing the line loss rate are extracted; calculating a reasonable range of the line loss rate of the low-voltage transformer area based on a neural network quantile regression model; and according to the calculated reasonable range of the line loss rate of the specific transformer area, diagnosing whether the transformer area is an abnormal transformer area, and adjusting the transformer area. Key factors influencing the line loss rate are extracted on the basis of actual operation data of an existing power utilization information system, an existing marketing system, an existing PMS system and the like, the reasonable range of the line loss rate can be given for a specific transformer area, and a reliable basis is provided for diagnosing a transformer area with abnormal line loss.