The invention provides a power distribution network power failure risk assessment method and system. The method comprises the steps of collecting power distribution network outage information; Substituting the power distribution network outage information into a pre-established power distribution network outage risk assessment model, and calculating outage risks; Wherein the pre-established powerdistribution network power failure risk assessment model comprises a power distribution network state variable sampling model and an assessment index. According to the technical scheme provided by theinvention, the outage model of each element is established, the risk assessment quantification index is clear, and the power failure risk level of the power distribution network containing the distributed power supply is assessed more accurately and comprehensively.