The invention discloses a test method for a plug-pull transformer of a GIS combined electrical apparatus without detaching the connectors, which does not need to plug or pull the connected plug-pull connector when the electronic transformer is tested, but to use an earth sleeve on the input-line earth switch which is arranged on the GIS combined electrical apparatus as the special transformer test sleeve to perform the test of the transformer; the improvement of the wiring in the test is: 1. an earth line on the input-line earth switch of the GIS combined electrical apparatus, which is connected with the transformer plug-pull connector, is untied; and the earth sleeve is insulated through a polyvinyl chloride insulation pyrocondensation sheath; 2. a polyvinyl chloride insulation cable sealing line with a diameter of 0.5mm<2> can be selected to perform the sealing seal between the GIS combined electrical apparatus and the transformer, and the line connection is guaranteed to be the shortest and without bending; and 3.a special test lead is used to test the DC resistance of the connection circuit. The test method without detaching the connectors can save the fund for purchasing special test sleeves and the cost for storing in storeroom, reduce labor intensity of testing personnel, shorten the time of power off, and has a wide application value in the power industry.