Violent torsional vibration occurred in a CSP rolling mill, and it got beating vibration shape. Based on the field measurement and theoretical analys is, the beating vibration in the torsion was found to be a fake one. The fake beating vibration in torsion was caused by the chatter marks on the working roll.When the steel plate contacted with the chatter mark area, forced vibration was stimulated in the main drive system with the frequency of the chatter marks; when theplate contacted with the other area with no charter marks, self excited vibration with system nature frequency took place, due to the negative damping phenomena. These two kinds of vibrations happened in the driving system one by one andtheir vibration amplitudes changed periodically, resulting in a beating shaped torsional vibration. The above result is valuable to interpret the vibration andto find the method for vibration control. Based on this, two methods were brought forward such as using the high speed steel roll. The experiment proved the methods effective.