In　order　to　keep　the　service　precision　of　electric　spindle　supported　by　hybrid　bearing,　the　method　of　reducing　static　and　dynamic　processing　force　by　electromagnetic　force　was　proposed　and　a　magnetic　lightening　system　was　developed.　Taking　the　grinding　machine　as　an　example,　the　dynamic　model　of　the　electric　spindle　system　was　established,　and　the　relationship　between　force　and　displacement　was　obtained.　The　static　and　dynamic　force　in　grinding　processing　were　analyzed　and　estimated.　Then　the　static　and　dynamic　load　demands　for　service　precision　keeping　of　electric　spindle　were　put　forward.　The　magnetic　lightening　system　was　designed　and　developed,　which　included　the　structure　modules　and　the　measurement-control　module.　Among　them,　the　feature　of　structure　module　was　the　universal　support　scheme,　and　the　measurement-control　module　supported　open　loop　and　closed　loop　control　strategies.　A　special　experiment　was　designed　to　verify　the　performance　of　the　magnetic　lightening　system.　It　is　showed　that　the　magnetic　lightening　system　can　satisfy　the　function　of　static　load　35　N　and　dynamic　load　28　N.　It　is　preliminarily　evidenced　that　using　electromagnetic　technique　to　reduce　machining　force　is　feasible.　For　the　electric　spindle　with　lightening　device,　it　is　more　effective　by　using　an　open　loop　load　control　strategy　of　artificial　adjusting.　©　2017,　Editorial　Office　of　Journal　of　Vibration　and　Shock.　All　right　reserved.