Liftable online cable defect detection device

A liftable cable online defect detection device comprises a support, a detection box, a detection piece and an adjusting assembly, the support comprises a base, a sliding rail, a sliding plate and a jacking driving piece, the sliding rail is vertically arranged on one side of the top face of the base, the sliding plate is slidably connected to the sliding rail, and the jacking driving piece is vertically arranged on the other side of the top face of the base; the output end of the jacking driving piece is fixedly connected with the bottom face of the sliding plate so as to drive the sliding plate to ascend or descend, a detection box is fixedly connected to the top of the sliding plate, a detection piece is arranged in the detection box, and an adjusting assembly is fixedly connected to the upper portion of the sliding rail and comprises two pulley blocks and two pulley block driving pieces. The pulley block driving part is in transmission connection with the pulley blocks and drives the pulley blocks to rota