Abstract: In this paper, the defect of a burning of the insulation screen of 110 kV cable insulation is analyzed. Through the sampling and anatomical inspection of the cable body, the possibility of ablation of the buffer layer caused by moisture entering the metal protective layer is excluded. Then, through the anatomical inspection of the flexible cable terminal, it is confirmed that the sheath at the connection between the lower part of the flexible terminal and the cable body is cracked, Make the inner cavity of the cable metal sheath form a channel with the external environment, so that the water blocking powder in the cable water blocking belt absorbs moisture and expands, gradually precipitates, and the water blocking belt is attached to the external shielding surface of the insulation. In view of this phenomenon, the improvement measures of checking the operation of the same type of flexible terminal cable in operation and avoiding the selection of flexible terminal with similar structure in equipment selection are put forward, which can achieve remarkable results.