The invention provides an active power distribution network fault positioning method based on current phase variations. According to the active power distribution network fault positioning method, anactive power distribution network simplification model containing distributed power supplies is established, sample data is effectively screened by means of current phases at two ends of a line measured based on a synchronous phasor measurement unit (PMU), current phases of valid data are extracted, a combination relation model between the current phases at both ends of the line is established, variations of the current phases before and after a fault and a two end current phase difference variable after the fault are obtained, an incidence relation between a fault section of the power distribution network and the current phases is established, a main cause of the current phase variations after the fault is determined, a concise and accurate protection action setting value is formed, further the protection is quickly and accurately started according to the protection action setting value, the fault is eliminated, quantitative information support is provided for power distribution network protection, the overall stability, rapidity and self-adaptability of the power distribution network are improved, and the active power distribution network fault positioning method has broad application prospects.