Grab dredger depth setting instrument with high depth detection accuracy

The utility model relates to the technical field of depth-keeping instruments, in particular to a grab dredger depth-keeping instrument with high depth detection accuracy, which comprises a touch display screen and a communication line, the top of the touch display screen is provided with the communication line, the other end of the communication line is provided with a depth-keeping instrument main body, and two sides of the communication line are connected with a support shell in a sliding manner. An output shaft of a motor drives a middle screw to rotate, the middle screw drives a middle gear to rotate, the middle gear drives gears on the two sides to rotate at the same time, the screw drives a threaded block to move, the threaded block drives a sliding block to slide along a sliding groove of a sliding rod, and meanwhile the threaded block drives a fixed pulley to move. The communication line is released along with descending of the depth setting instrument, the depth setting instrument is submerged into