A safe operation range based line N-1 verification method for a medium-voltage power distribution system is provided, and the method includes: inputting medium-voltage power distribution system structure information which is used for topology structure analysis on the medium-voltage power distribution system, so as to work out contact information among the lines; performing wiring mode analysis on the medium-voltage power distribution system; reading working point information of the medium-voltage power distribution system; providing a safe boundary of the safe working range of the lines of the medium-voltage power distribution system; calculating a safe distance from the working point of the medium-voltage power distribution system to the safe boundary of the safe working range of the lines; determining an operational state of the working point of the medium-voltage power distribution system; and providing a line N-1 verification result of a power grid of a researched region. The method of the present invention can describe the existing working point of the power distribution system based on the interconnection relation among feeder lines from the angle of the grid structure of the power distribution system, so as to further describe the boundary of the safe working range of the lines of the medium-voltage power distribution system, and calculate the safe distance from the working point of the system to the boundary of the safe working range of the lines; more comprehensive safety information can also be provided, and therefore the method is more suitable for application in real-time scheduling and operation.