Abstract: Starting from the equivalent replacing radiation model of a single pair of unshielded multi-core wires with a single pair of large current injection, a test method for strict equivalent radiation of a single pair of large current injection is proposed. Taking the unshielded four-core wire as the test object, the terminal response law of the unshielded multi-core wire is explored, and it is found that each pair of wires can not be strictly equivalent at the same time. The equivalent test method of tightening the coupling channel of unshielded wire is proposed and verified by the test. The test results prove that the proposed method of equivalent injection of bulk current tightening can replace the strong field irradiation test, which solves the problem of the passing ability test of the weapon equipment system.