The finite element model of NC Machine spindle box is set up by COSMOS/Works

and modal analysis of the spindle box is done

then the natural frequencies and the vibration modes are calculated.On that basis

the dynamic characteristic of spindle box is optimized through defining multi structure sizes as design variable.Fundamental frequency of the spindle box is increased obviously after optimizing;as a result

damping property of it is enhanced effectively.A group of structural parameters with fine dynamic characteristic are calculated

which offer significant referents to structure design of spindle box.