The invention discloses a safety analysis method of an active distribution network based on safety distances, comprising the steps of constructing an active distribution network safety boundary composed of an active distribution network full-quadrant safety domain and N-0 and N-1 safety restraints employing equal size; acquiring a spatial geometric distance of a working point from position a to position b and variation of system state; defining a shortest/longest safety distance, a safety domain shortest/longest safety distance, a vertical safety distance, and an axial safety distance; calculating a shortest geometric safety distance, a longest geometric safety distance, shortest and longest state safety distances, safety domain shortest and longest safety distances, a vertical safety distance, an axial safety distance, and a domain axial distance; performing safety judgment, safety level analysis, boundary-crossing direction analysis and positive and reverse boundary-crossing analysisbased on the safety distances. The method can precisely provide the most dangerous and safest directions of variation for a current working point as well as margins in these directions.