The invention provides a multiple-device body serial transformer test method, assembly and test system. The method comprises the following steps that: the high-voltage line of a test device is connected with the high-voltage winding of a transformer, and the low-voltage line of the test device is connected with the low-voltage winding of a device body to be tested; the low-voltage windings of other device bodies other than the device body to be tested in the transformer are short circuited; and the test device is adopted to test the device body to be tested. With the multiple-device body serial transformer test method, assembly and test system provided by the embodiments of the present invention adopted, when the device body to be tested is tested, no magnetic flux is generated in the other device bodies during testing, and therefore, the influence of the remanence of an iron core can be effectively eliminated, and the accuracy of a test result can be improved.