The invention relates to a test system for simulating a fault of poor grounding of the end screen of an oil-immersed inverted CT. The characteristics are that the test system includes a sleeve (5), a capacitive screen (6) is installed in the sleeve (5), the top of the sleeve (5) is equipped with an oil storage cabinet (4) and an expander (1) in sequence, the bottom of the sleeve (5) is equipped with a pedestal (8), a end screen grounding terminal (9) electrically connected with a end screen (7) of the abovementioned capacitive screen (6) is installed in the pedestal (8), and the end screen grounding terminal (9) is connected with a grounding bolt on the pedestal (8) through a discharge sphere gap (10). The test system provided by the invention can be used for studying a development process and discharge pulse characteristics of the fault of the equipment in a high voltage alternating current system. Through acquisition and analysis of the discharge pulse characteristics in a laboratory, qualitative and quantitative analyses of corresponding defects can be made, thereby providing a theoretical basis for further study in the laboratory and providing reference for practically detecting the fault on site.