Hydraulic centering system and method for uncoiling machine of rolling mill

The invention provides a hydraulic centering system for an uncoiling machine of a rolling mill. The hydraulic centering system comprises a transmission side oil cylinder, an operation side oil cylinder, a first three-position four-way reversing valve and a second three-position four-way reversing valve, and the extending end of the transmission side oil cylinder abuts against the left side of a strip; the extending end of the operation side oil cylinder abuts against the right side of the strip; two oil ports of the first three-position four-way reversing valve are connected with a liquid inlet and a liquid outlet of the transmission side oil cylinder through oil lines correspondingly, and other two oil ports of the first three-position four-way reversing valve are connected with a pressure oil pipe and an oil return pipe correspondingly; and two oil ports of the second three-position four-way reversing valve are connected with a liquid inlet and a liquid outlet of the operation side oil cylinder through oil