Several　kinds　of　evaluation　methods　for　the　uncertainty　in　coordinate　measurement　are　introduced　and　it　points　out　that　most　of　these　methods　are　failed　to　the　uncertainty　evaluation　for　special　objectives　because　of　lack　of　theory　support　or　practicability.　Therefore,　this　paper　investigates　the　uncertainty　evaluation　of　gear　measurement　with　Coordinate　Measurement　Machines　(CMMs)　by　the　Monte　Carlo　method.　Firstly,　a　measuring　model　is　established　based　on　the　files　for　the　calibration　and　compensation　of　the　specific　CMM,　then　the　mode　is　used　to　obtain　measuring　results　with　a　large　number　of　sample　points.　Using　these　simulated　results,　the　uncertainties　can　be　evaluated　more　conveniently.　Finally,　the　Monte　Carlo　method　is　successfully　used　in　evaluating　measurement　uncertainty　of　gear　profiles　and　obtained　stable　results　show　that　the　maximal　difference　among　the　results　is　less　than　0.03　μm　when　the　typical　uncertainty　is　0.96　μm.　The　paper　suggests　that　Monte　Carlo　method　can　support　specific　uncertainty　measurement　and　can　change　the　situation　that　common　evaluation　method　can　not　be　suitable　for　the　commercial　CMMs.