The invention discloses a distribution network protecting method which is characterized by comprising the following steps of on the condition that a fault occurs in a currently protected line, calculating an initial setting current value at the head end of the currently protected line; calculating a maximal back-end motor feedback current value at the head end of the currently protected line; calculating the fault current value in a least operation mode at the head end of the currently protected line; and using a maximal value in the initial setting current value, the maximal back-end motor feedback current value and the fault current value in the least operation mode at the head end of the currently protected line as the set value of the setting current of the currently protected line. The distribution network protecting method has advantages of reducing effect of a motor feedback current to a non-fault line protecting device, setting protection of a same subsection switch in different operation modes to a same value, simplifying a protection setting method, and greatly improving reliability and selectivity in protection. The distribution network protecting method is suitable for the distribution network which has an automatic function and is provided with multiple subsection switches.