The invention relates to a power distribution network direction over-current protection online setting method and system for access of a distributed power supply. The method comprises the following steps: obtaining a distributed power supply and basic parameter information and real-time operation data of a feed line which the distributed power supply is accessed to from a distribution automation system; based on the basic parameter information and the real-time operation data, establishing a feed line short-circuit calculation model of the feed line; based on the feed line short-circuit calculation model, performing short-circuit current calculation on the feed line to obtain short-circuit current values of the feed line; based on the short-circuit current values, carrying out sensitivity verification on over-current protection fixed values of the distributed power supply and the feed line; and when the result of the sensitivity verification is unqualified, based on the short-circuit current values, carrying out online setting calculation on the distributed power supply and the feed line. According to the power distribution network direction over-current protection online setting method and system for the access of the distributed power supply, online recalculation is performed on the over-current protection fixed values according to change of the operation mode of a power distribution network, such that the adaptability of the protection fixed values to the current operation mode of the power distribution network is improved, and calculation of the protection fixed values is optimized.