The invention provides a power distribution network reliability evaluation method and a power distribution network reliability evaluation system. The power distribution network reliability evaluation method comprises the steps of: establishing a reliability model for each set of power transmission equipment in a power transmission network, so as to obtain a power transmission equipment reliability model group; extracting samples from the power transmission equipment reliability model group, performing state estimation on the extracted samples, and eliminating power transmission network failures according to a state estimation result; calculating a maximum output capacity index of the power transmission network after eliminating the power transmission network failures; judging whether power supply capacity of the power transmission network is adequate; establishing a reliability index of each load point in the power transmission network if the power supply capacity is adequate; performing load-power supply model equivalent transformation on the reliability index of each load point in the power transmission network, so as to obtain a reliability index of each power supply node in the power distribution network; and calculating an overall reliability index of the power distribution network according to the reliability index of each power supply node in the power distribution network. By adopting the power distribution network reliability evaluation method and the power distribution network reliability evaluation system, the precision and integrity of the power distribution network reliability evaluation result are improved.