To　protect　free-standing　object,a　rectangular　object　is　taken　as　example　and　by　SIMULINK　technique　its　oscillation　response　under　earthquakes　were　studied.Based　on　static　and　dynamic　balance　theories,oscillation　conditions　as　well　as　motion　equations　of　the　free-standing　object　under　earthquakes　were　deduced;Based　on　SIMULINK　model,simulation　analysis　on　the　object　under　both　level　and　vertical　earthquakes　were　carried　out,parameters　such　as　initial　conditions,earthquake　intensity　and　ratio　of　width　of　the　object　against　its　height　(B/H)　and　so　on　were　discussed.Results　show　that　under　earthquakes　oscillation　conditions　of　the　object　relate　closely　to　B/H,earthquake　intensity　and　friction　coefficient　between　object　and　its　base;Under　earthquakes　oscillation　response　of　the　object　is　sensitive　to　initial　conditions,and　the　response　becomes　more　serious　under　less　B/H　or　larger　earthquake　intensity　conditions.　Besides,　SIMULINK　technique　can　effectively　simulate　oscillation　response　of　free-standing　object　under　earthquakes,which　proves　the　technique　useful.