Abstract: Addressing the problems as staying with the hydraulic system of the precision-centering device of the edge-milling machine,namely frequent oil leakage,serious noise pollution,high investment and maintenance workload of the equipment,etc.,the said centering system is improved by substituting the Siemens servo centering system for the conventionally-used hydraulic one. Relevant practice proves that the improvement action has brought about such advantages as meeting the workshop production requirements,enhancement of the centering accuracy of the steel plate,simplifying the equipment configuration of the edge-milling machine unit, saving the investment, improving the production environment,and reduction of both the equipment failure rate and the follow-up maintenance work,resulting in significant effect.