The utility model provides a multi-interface coupler testing wire comprising even pigtail fibers. First coupler plugs and second coupler plugs are welded on the two ends of each pigtail fiber. The first coupler plugs are matched with coupler sockets installed on an intelligent relay protection tester. The second coupler plugs are matched with coupler sockets installed on an intelligent device to be tested. Therefore, an unmatched case between the coupler plugs of the testing wire and the coupler sockets installed on the intelligent device to be tested is no longer present. When an intelligent relay protection testing device tests an intelligent device to be tested, a testing requirement is satisfied just by one testing wire such that complex operation is prevented that multiple testing wires are used in combination or a tester is replaced, thereby saving time.