The invention discloses a distribution network line distance protection method after the connection of a large-scale distributed photovoltaic power supply. The method comprises the following steps of:in view of the over-range protection misoperation at a distribution network photovoltaic downstream fault line system side, setting relatively short-delay three-stage directional circle characteristic distance protection at a line system side at the downstream of a photovoltaic power supply grid-connected point; in view of the incapability of cutting off a fault at a photovoltaic upstream fault line load side, setting relatively long-delay three-stage directional circle characteristic distance protection at a line load side at the upstream of the photovoltaic power supply grid-connected point; and enabling the two protection methods to cooperate with the current protection of a bus head end out line system side without the connection a the photovoltaic power supply. The distribution network line distance protection method is not affected by a photovoltaic output condition, solve the difficult setting calculation of the protection current threshold of the downstream line system side after the connection of the photovoltaic power to the distribution network power supply circuit, and incapability of cutting off the photovoltaic fault current of the photovoltaic connection point upstream load side, guarantees reliable removal of line faults, and improves the system operational safety and reliability of the photovoltaic connection distribution network.