The　incremental　acquisition　method　of　rules　is　a　topic　in　data　mining.　Based　on　rough　set　theory,　the　incremental　rule　acquisition　method　based　on　genetic　algorithm　is　studied　in　two　aspects　of　the　acquisition　and　optimization　decision　of　rules.　The　knowledge　based　on　rough　set　representation　and　measurement　is　constructed　by　the　study　on　decision　table　and　decision　rule　coefficients,　and　a　new　optimization　algorithm　is　obtained　by　the　combination　of　genetic　algorithm　with　rule　mining　algorithm.　Thus,　a　new　incremental　decision　rule　acquisition　algorithm　is　presented,　and　it　is　of　the　advantages　of　simple　structure,　high　search　efficiency　and　high　solving　speed.　The　new　algorithm　is　an　incremental　approach　to　updating　the　existing　decision　rules　in　database　and　their　parameters　when　various　new　objects　are　appended　to　the　decision　table,　instead　of　running　the　whole　learning　process　again.　Experimental　results　show　that　the　algorithm　can　effectively　acquire　optimal　rules　with　incremental　GA.