The invention discloses a DEA-based (Data Envelopment Analysis-based) power grid line loss potential analysis method. The method includes the following steps: whether the purpose of the method is to determine the different voltage classes of a power grid or the loss reduction spaces of different elements is determined; an index system of the line loss potential analysis method is determined; a basic model of a DEA algorithm is determined, and a line loss potential analysis method model is created. The method divides the different voltage classes or the different elements into a plurality of decision-making units, and with line loss-affecting indexes as variables, by analyzing the input-output data of samples, the method determines the effective decision-making units, so that the efficiency of each decision-making unit, i.e. the loss reduction potential of each decision-making unit, is determined. The specific steps are shown in the drawing of the abstract. The invention solves the problem that power distribution networks cannot scientifically calculate loss reduction potential.