The invention relates to an active power distribution network fault positioning method, and belongs to an electric power automation technology. According to the method, a transformer substation (1), transformer substation outlet wire switches (2) and a plurality of segmentation switches are adopted, wherein the transformer substation outlet wire switches (2) are sequentially arranged along an outlet wire of the transformer substation (1), and one or a plurality of distributed power supplies are arranged in a section formed between the transformer substation outlet wire switches (2) and the adjacent segmentation switches and/or between the adjacent segmentation switches. The active power distribution network fault positioning method is characterized by comprising the following steps that a, an FTU monitors the current value of a power distribution network switch; b, whether the current value exceeds the setting valve or not is judged; c, the FTU reports the result to a master station; d, the master station judges the positions of fault points segment by segment; e, whether the Rho value meets the judgment condition or not is judged; f, the positions of fault points are determined. The method has the advantages that the addition of a voltage transformer is not needed, the positioning of the power distribution network fault segment can be realized, the increase of the original excessive current setting value is not needed, and the fault detection sensitivity is ensured.