The present invention discloses an active distribution network fault section location method and system based on a positive sequence current fault component. The method comprises the steps of: collecting three-phase currents flowing through switches at two sides of a protected feeder circuit in real time; after it is detected that a feeder generates faults, calculating and obtaining the amplitudesand the phases of the positive sequence current fault components at the two sides of the protected feeder; calculating a starting amount and a brake threshold; and when the starting amount of n continuous sampling points in a certain circuit is larger than the brake threshold, determining that the section is a fault section. The simulation analysis shows that: for a distribution network includingdifferent types of DG, when different types of faults are generated at different positions, the active distribution network fault section location method and system can accurately identify the faultsection, are good in tolerance transition resistance capacity, high in sensitivity and high in reliability, and are good in economical efficiency with no need for fault line selection and voltage information.