Dynamic performance analysis and dynamics modification is a fundamental approach that obviates faults of strap rolling mills in operation. An integration method is provided in order to avoid instability vibration for strap rolling mills in this paper. First, the control system operation parameter and structural vibration signal of rolling mills are acquired. Then control system identification is performed by means of support vector regression method. On that basis, the fault of the control system is diagnosed by means of identified model. The concept and technique of the link dynamics are provided to build mixing model of control system and mechanical structures, and the simulation and analysis of the operation stability in different structure damage condition are carried out. Finally, instability vibration of rolling mills due to structural damage and inappropriate design is cleared up by means of structural dynamics modification and redesign.