The invention relates to a relay protection system of an electric distribution network longitudinal zero-sequence acceleration action. The relay protection system comprises an electric distribution network station with double power supplies, wherein all first bus outlet protection devices and all second bus outlet protection devices are connected with a section switch protection device; the section switch protection device is connected with a section current transformer and a section switch; section bus three-phase current on a section bus is obtained through the section current transformer; if at least one phase in the section bus three-phase current exceeds a section bus longitudinal zero-sequence protection current setting value preset in the section switch protection device, the section switch protection device performs timing; after the section longitudinal zero-sequence action long time limit tZXL, the section switch protection device controls the section switch to be in a switch-off state. The relay protection system has the advantages that the structure is compact; the inside fault main protection action time of the electric distribution network station is effectively shortened; the problem of electric distribution network and main network relay protection setting time matching difficulty is solved.