Basically, the change is very small, and there is indeed deformation or change in actual use. It depends on the type of rolling mill, such as cogging mill. If there are more passes and more rolls, the surface will be worn, which is similar to polishing, and the roughness will be reduced, so the roll surface will definitely be deformed. In addition, if there are CVC type plate rolls or convex rolls, the parameters of arc or roll shape will change after cogging and changing rolls, which proves the deformation of rolls from another angle. Due to frequent roll change, the deformation of the finished rolling mill is almost negligible. When changing rolls, we should not only consider the accidental damage, fatigue damage and roughness change of roll surface caused by multi-pass rolling, but also consider the change of roll shape.