The invention discloses a test cavity for testing low-boiling insulation liquid insulation characteristic, comprising a cavity, an insulating sleeve flange, an electrode, a blind plate flange, a transverse heating flange mechanism and a longitudinal heating flange mechanism. The cavity comprises a cavity body and an observation window fixed to the head end and the tail end of the cavity body. Thecavity body is of an internally hollow shell structure, and a plurality of flange mounting holes are formed in the side wall of the cavity body. The insulating sleeve flange, the blind flange, the transverse heating flange mechanism and the longitudinal heating flange mechanism are arranged in cooperation with the flange mounting holes, so that the test cavity has two structures of lateral test and longitudinal test, and the two test schemes can be flexibly adjusted. One end of the electrode extends into the cavity body, and the other end of the electrode penetrates through the sleeve flange to be locked and fixed through a sealing pressing cap. According to the invention, online adjustment of the electrode can be completed by pumping the electrode rod after the external screwing sealing pressing cap, and even the the test scheme for liquid in the cavity can be changed without removing liquid by rotating, replacing the top flange of the cavity and the like.