The invention discloses a back-to-back GIS high-voltage cable connection device for testing. At present, domestic cable manufacturers or scientific research institutions have carried out a large number of high-voltage cable defect simulation tests. During the test process, a defected cable section needs to be replaced frequently; however, no isolation measures are taken to separate a defected cable section from a non-defect cable section based on the common test designs, so that the workload is high, the period is long, and testing materials are wasted during each replacement process. The back-to-back GIS high-voltage cable connection device comprises a GIS cabin body and two high-voltage cable terminals. The two high-voltage cable terminals are inserted into the GIS cabin body respectively from the two sides of the GIS cabin body; and two conductor connection shafts of the two high-voltage cable terminals are in a firm butt joint in the GIS cabin body based on a detachable structure.On the basis of the ingenious structure, the butt joint of the two high-voltage cable terminals is realized and the butt-joint part employs a detachable structure, so that isolation of the defected cable section for testing is realized. Therefore, defected cables can be replaced conveniently during the test process; the cost is lowered; and the test efficiency is improved.