The utility model relates to an anti-blockage and anti-oil leakage positioning device for back-up roll lining, a pin hole facing downwards is arranged on the back-up roll bearing chock and the lining, the center of which points to that of the back-up roll shaft journal; a taper-shaped positioning pin is plugged into the pin hole, the positioning pin is provided with a key groove and a bolt hole, a key and a pressing bolt are arranged to fit the key groove and the bolt hole, so that the positioning pin can fix in the bearing chock. Combined with the weight of the positioning pin, the design of certain angle of the positioning pin can tremendously increase the difficulties for the positioning pin to move outwards resulting from falling off by vibration, so that the utility model can function as anti-blockage and anti-oil leakage, and can solve the problems of that the finishing back-up roll assembly can not be pulled out due to the positioning failure of the back-up roll lining of finishing mill.