In modern industries, in whichwhere high productivity is one of the most important concerns, machine tools are facing difficulties to satisfy the high high-speed operation, while and at the same time achieve the precision machining. Generally, the vibrations of the structure increase proportionally to the square of the operating speed so that the precision machining is severely damaged with increased speed. which is a must for the high productivity. Therefore, the suppression of the structural vibrations of the machine tools is the a major concern in the machine tool industry in order to achieve the high productivity and the precision machining simultaneously. In this study, the dynamic properties of a machining center structure were analyzed through the experiment and the computer simulations, and furthermore the results from those were compared to confirm the validity of the simulation model. The design alterations were deduced from the analysis and applied to the simulation model to investigate the effects of those alterations to suppress the vibrations of the machine. The result shows that the relatively simple design alterations, without redesigning the main structure of the machine, can suppress the vibrations effectively.