The invention provides a loss reduction potential estimation method and device for a power distribution network. The method includes obtaining index values of the power distribution network in different target areas; giving scores of different index values according to a predetermined score giving standard and obtaining score values corresponding to the index values in the target areas; obtaining the score values of different target areas in a criterion layer of a power distribution network energy efficiency assessment index system; ranking the comprehensive score values of a solution layer of power distribution network of the target areas from small to large; and determining a to-be-modified target area according to the ranking result. The device includes an index value obtaining unit, a score giving unit, a criterion layer score value obtaining unit, a comprehensive score value obtaining unit, a first ranking unit and a to-be-modified target area determining unit. According to the invention, loss distribution condition of equipment during an operation process can be displayed, so that energy efficiency improvement emphasis can be found.