The utility model discloses an auto -lock roll that the drunkenness just can not cause the damage to locking device can not take place when rolling. Including top tread roller and bottom roll, it radially is equipped with round roller platform to be close to end department on the top tread roller, the outer terminal surface of roller platform is the inclined plane, the orientation slope of inclined plane terminal surface in to the roller platform, be equipped with on the bottom roll with roller platform assorted recess, the inclined plane of roller platform coats and is stamped the elastic layer. It is spacing to utilize roller platform and the recess on the bottom roll on the top tread roller to carry on both, realizes the auto -lock of roll, and the axial force that the bottom roll received can be offset to the inclined plane and the face of recess correspondence of roller bench, guarantees can not take place the drunkenness when rolling, can not damage locking device, can improve rolling size precision to set up the elastic layer on the inclined plane of roller platform, avoid causing the damage because of taking place relative friction between roller platform and the inclined plane.