Chatter　is　a　kind　of　self-excited　vibration　which　may　occur　in　the　milling　process　and　has　several　negative　effects　such　as　poor　surface　quality　and　severe　tool　wear.　This　paper　presents　an　active　chatter　control　method　based　on　H∞　almost　disturbance　decoupling　problem　with　measurement　feedback　and　with　internal　stability　(H∞-ADDPMS)　and　piezoelectric　stack　actuators.　First,　a　milling　process　model　considering　regenerative　effect　is　constructed　to　find　out　the　milling　conditions　when　chatter　occurs.　Then,　the　whole　active　control　system　and　constructing　procedure　of　an　active　controller　based　on　H∞-ADDPMS　is　proposed.　Next,　the　milling　process　is　simulated　and　the　H∞-ADDPMS　controller　is　calculated　based　on　cutting　force　coefficient　identification,　frequency　response　experiments,　and　modal　analysis　technique.　Finally,　the　active　control　experiment　is　carried　out　on　a　computer　numerical　control　(CNC)　milling　machine　to　verify　the　feasibility　and　effectiveness　of　the　proposed　active　control　strategy.　©　2018,　Springer-Verlag　London　Ltd.,　part　of　Springer　Nature.