The invention relates to a three-roller hydraulic wringing device of a cold rolling mill. The device mainly comprises oil cylinder base plates which are respectively arranged on two ends of a holder, wringing oil cylinders which are fixedly arranged on the oil cylinder base plates, lower slide seats which are arranged under two sides of the holder, lower bearing seats which are arranged on the lower slide seat, and a lower wringing roller two ends of which are respectively arranged in the lower bearing seats on the two sides. The device is characterized by further comprising upper slide seats which are arranged above two sides of the holder and provided with upper bearing seats, an upper wringing roller two ends of which are respectively arranged in the upper bearing seats on the two sides, wherein, a piston rod and a joint of the wringing oil cylinder are respectively connected with the upper slide seats under two sides and drive the upper slide seats to move up and down. The device is provided with an upper wringing roller, thus completely removing cooling fluid remained on a surface of a strip material, avoiding scratch of a surface of strip steel and ensuring the quality; the device has the advantages of higher automaticity, simple and convenient operation, safety and reliability, and convenient installation and maintenance; a hydraulic cylinder acts to drive the wringing roller to work, which can improve the work efficiency.