The invention discloses an active voltage arc-extinction method applicable to a single-phase earth fault of a medium voltage distribution network, and relates to the technical field of fault self-recovery of a medium voltage distribution network. The active voltage arc-extinction includes the following steps: a. continuously measuring bus three-phase voltage, zero sequence voltage and each outlet three-phase current, and when a single-phase earth fault is detected, conducting fault phase selection; b. designating a threshold Ires.g of a fault phase current magnitude and a threshold Ures.g of a fault phase voltage magnitude of a fault feeder; c. measuring the voltage and current of the fault phase, comparing the fault phase current magnitude of the fault feeder with Ires.g. According to the invention, the method can effectively increase the arc extinction of a low-resistance earth fault, and compensate current at a fault point as much as possible while excess voltage is effectively controlled, and ensures that arc at the fault point can be reliably extinct. According to the invention, for non-linear resistance earth, the method is also effective simply by changing program codes in current active compensating apparatuses, and has higher values when applied to engineering.