The utility model discloses a hard disk recording system which comprises a hard disk recorder, a video display device and at least one video camera, wherein the hard disk recorder is in signal connection with the video display device, and a first twisted-pair cable interface, a differential demodulation module and a signal output module which are sequentially connected are arranged in the hard disk recorder; the first twisted-pair cable interface is connected with the video camera through a twisted-pair cable so as to receive video signals of the video camera after differential processing; the differential demodulation module is used for demodulating the video signals after the differential processing; and the signal output module is used for transmitting the video signals after demodulation to the video display device. The hard disk recording system adopts the twisted-pair cable for transmitting the video signals between the video camera and the hard disk recorder, thereby not only extending the transmission distance and expanding the range of application of the hard disk recording system, but also reducing material cost, simultaneously reducing intermediate conversion link of a signal transmission path, improving the transmission stability, ensuring the transmission quality, and avoiding or reducing the phenomena of video distortion, time delay and the like.