Zircon　U-Pb　dating　and　whole-rock　geochemical　analysis　have　been　performed　on　Late　Jurassic　-　Early　Cretaceous　intrusive　rocks　of　the　Ulanhot　area,　NE　China,　with　the　aim　of　constraining　the　tectonic　evolution　of　the　central　and　southern　Da　Xingan　Range.　Zircon　U-Pb　dating　indicates　that　Late　Jurassic　-　Early　Cretaceous　magmatic　events　experienced　four　stages　at:　c.　155　Ma;　c.　144　Ma;　135-130　Ma;　and　c.　126　Ma.　The　c.　155　Ma　magmatic　event　consists　of　quartz　diorite　and　granite-porphyryp　with　the　geochemical　characteristic　of　high　Sr　and　Sr/Y　or　high　A/CNK　(1.38),　implying　the　primary　magma　was　derived　from　partial　melting　of　a　thickened　lower　crust　which　induced　the　closure　of　the　Mongol-Okhotsk　Ocean.　The　c.　144　Ma　magmatic　event　consists　of　quartz　monzodiorite　with　the　geochemical　characteristics　of　alkaline　series,　and　indicates　the　delamination　of　a　thickened　crust.　The　135-130　Ma　magmatic　event　consists　of　syenogranite　and　granite-porphyry　with　characteristics　of　both　I-type　and　A-type　granites,　which　induced　both　the　subduction　of　the　Palaeo-Pacific　oceanic　plate　and　the　post-orogenic　extension　of　the　Mongol-Okhotsk　Orogenic　Belt.　The　c.　126　Ma　magmatic　event　consisted　of　highly　fractionated　I-type　biotite　granite　and　alkaline　series　gabbro,　marking　the　end　of　the　Mongol-Okhotsk　Orogen,　and　implying　that　the　study　area　was　controlled　by　the　circum-Pacific　tectonic　system　during　this　stage.