The invention provides a hydraulic automatic cable feeding device of an anchor cable. The hydraulic automatic cable feeding device comprises a rack, wherein one end of one end face of the rack is fixedly provided with a fixed clamping device which is connected with a fixed guide pipe, the other end of one end face of the rack is movably provided with a slidable clamping device capable of sliding along the rack, the slidable clamping device is fixedly connected with a movable guide pipe, the movable guide pipe is in sliding sleeving with the fixed guide pipe, each of the fixed clamping device and the slidable clamping device is internally provided with a clamping piece which is driven by a hydraulic cylinder and is used for clamping an anchor cable, a telescopic cylinder is arranged in the rack, one end of the telescopic cylinder is connected with one end, close to the fixed clamping device, of the rack, and the other end of the fixed clamping device is connected with the slidable clamping device. Through combined application of multiple groups of hydraulic cylinders, the problem of difficulty in cable entering of anchor cables in the prior art is successfully solved, and the construction safety is ensured. The construction efficiency is improved by 3-5 times compared with the cable feeding manner that workers are cooperated with a hoist. The hydraulic automatic cable feeding device is particularly suitable for cable feeding and cable entering construction of elevation anchor cables.