In　the　inking　system　of　an　offset　printing　press,　a　vibrator　roller　distributes　ink　not　only　in　the　circumferential　direction　but　also　in　the　axial　direction.　In　the　control　process,　if　ink　amount　is　determined　only　by　the　dot　area　coverage　without　considering　the　impact　of　vibrator　roller＇s　oscillation,　the　printing　colour　quality　will　be　reduced.　This　paper　describes　a　method　of　calculating　the　impact　factor　of　vibrator　roller＇s　oscillation.　First,　the　oscillation　performance　is　analyzed　and　sample　data　of　impact　factor　is　got.　Then,　a　fuzzy　controller　used　for　the　calculation　of　the　impact　factor　is　designed,　and　genetic　algorithm　is　used　to　optimize　membership　functions　and　obtain　the　fuzzy　control　rules　automatically.　This　fuzzy　controller　can　be　used　to　calculate　impact　factors　for　any　printing　condition,　and　the　impact　factors　can　be　used　for　ink　amount　control　in　printing　process　and　it　is　important　for　higher　printing　colour　quality　and　lowering　ink　and　paper　waste.　©,　2015,　Inst.　of　Scientific　and　Technical　Information　of　China.　All　right　reserved.