A　hybrid　method　was　proposed　based　on　the　combination　of　parameter　sensitivity　analysis　and　sequential　optimization,　a　parameter　model　for　550　mill　housing　was　established,　and　the　dimensions　were　optimized　with　ANSYS,　where　minimizing　volume　was　considered　as　the　first　objective　function.　According　to　the　optimized　results　and　the　sensitivity　analysis,　a　further　optimization　was　carried　out　for　minimizing　displacement　in　x　direction　as　the　second　objective　function,　which　is　more　precise　than　the　conventional　single　strategy,　and　avoids　the　difficulty　due　to　determination　weight　coefficients　in　multi-objective　method　to　show　the　validity　and　effectiveness.