The invention relates to an automatic grinding device. The automatic grinding device comprises two mutually-parallel grinding tool bodies, a rotary grinding cylinder, a linear grinding cylinder and a frame, wherein the rotary grinding cylinder is used for controlli8ng the grinding tool bodies to rotate; the linear grinding cylinder is used for controlling the grinding tool bodies to perform rectilinear motion; the frame is connected with the grinding tool bodies, the rotary grinding cylinder and the linear grinding cylinder; the automatic grinding device also comprises a bearing seat and a hoisting device, wherein the bearing seat is used for supporting the grinding tool bodies, and the hoisting device is used for hoisting; two frames are respectively mounted at the two ends of the two parallel grinding tool bodies; the other side of one frame is connected with the linear grinding cylinder. The grinding tool is capable of realizing automatic grinding on 20 frame holes of a rolling machine by rotation motion and rectilinear motion of the grinding tool bodies and is also capable of guaranteeing the requirements on toughness and parallelism degree of the frame holes.