The　study　for　the　impacts　on　the　machining　accuracy　of　heavy　gantry　machine　of　uneven　foundation　settlement,　there　is　a　heavy　gantry　machine　for　study.　Assuming　the　machine　base　produce　two　differential　settlement　because　of　the　uneven　foundation　settlement,　the　whole　machine　tool　structure　deformation　caused　by　the　differential　settlement　let　tool　tip　have　an　offset　position　and　angle　that　affect　the　machining　accuracy.　This　paper　established　the　model　to　study　the　impacts　on　the　machining　accuracy　of　heavy　gantry　machine　of　uneven　foundation　settlement　on　the　basis　of　the　overall　model　of　the　machine　to　simplify,　can　provide　theoretical　and　technical　guidance　for　the　design　or　the　structural　optimization　or　error　compensation　of　heavy　gantry　machine.