By　the　experimental　modal　testing　to　the　main　structure　of　a　high-speed　horizontal　machining　center,　the　modal　parameters　such　as　the　natural　frequency,　damping　ratio,　stiffness　and　mode　shapes　are　obtained.　By　analyzing　the　dynamic　characteristics,　the　weak　links　of　this　structure　is　at　the　spindle　front　bearing　and　the　vertical　column　on　which　the　screw　driving　the　spindle　box　to　move　in　vertical　direction　is　mounted　are　determined,　and　provide　an　important　basis　of　optimizing　the　structure　for　the　machining　center.　And　the　amplitude-frequency　characteristic　curves　of　the　weak　structure　evaluate　the　dynamic　stiffness　as　the　key　indicators　to　provide　reliable　data　for　improving　processing　accuracy　and　cutting　ability　of　machining　center.　The　analysis　results　show　that　experimental　modal　analysis　is　a　effective　test　method　for　improving　the　anti-vibration　performance　and　machining　stability　of　domestic　machining　centers.