The invention discloses a water content detecting device for cables. The water content detecting device for the cables comprises a cabinet, a worktable is arranged at the upper end of the cabinet, anupper mounting plate is fixed at the upper end of the worktable through support poles, cable guiding rollers are arranged at the lower end of the mounting plate and the upper end of the worktable, a cable is connected onto outer walls of the cable guiding rollers in a rolling manner, a fixed frame is welded to the upper end of the worktable, an electronic scale is arranged at the upper end of thefixed frame, a cable collection wheel is mounted on an inner wall of one support pole, the cable is rotatably connected with an outer wall of the cable collection wheel through an input end face of the electric scale, and a motor is mounted on the inner wall of the one support pole. The water content detecting device for the cables has the advantages that through the arranged cabinet, the cable guiding rollers, the upper mounting plate, a protection box, the electric scale, the cable collection wheel, an operation panel, an alarm, a control table, an air heater, a drying box, a cable guiding hole and a processer, the problems of low accuracy and low working efficiency of existing detecting equipment are solved.