The invention provides a cable core automatic straightening device which is formed by a machine frame part, a sliding base part, a sliding base fixing device, a power transmission part and a cable core winding part. The machine frame is of a rectangular frame structure capable of being spliced in a segmented mode, a linear guide rail is arranged on the upper portion of the machine frame, the sliding base part comprises the sliding base matched with the guide rail, a sliding plate fixed to the sliding base and a cable end fixing device installed on the sliding plate, the cable end fixing device comprises a fixed clamping plate, a movable clamping plate, a fixed nut plate and a lead screw, the fixed clamping plate and the fixed nut plate are fixed to the sliding plate, the fixed nut plate and the lead screw form a lead screw pair, and the movable clamping plate is fixed to one end of the lead screw. The cable core automatic straightening device is convenient and flexible to operate, high in cable processing speed and good in straightening effect and solves the problems that a cable core cannot continuously operate when being straightened by workers, the speed is low and the workers are tired due to long-time strength exertion.