Cenozoic allkaline basalts in Northeast China contain abundant upper mantle- derived ultramafic nodules.According to the pressure and depth of the formation of the ultramafic nodules estimated by geobarometric method, the depth of generation of the basaltic and pyroxenitic magmas and geophysical data, a preliminary compositional model of the upper mantle beneath Northeast Chiria has been established. If the overlying crust-mantle transition zone above the Moho is included, five layers have been recognized as follows:l)the crust-mantle transition zone (28-35km)，2) the spinel 1herzolite layer (35-120 km)，3 the low-velocity zone containing trace amount of silicate melt from 60 to 120km; 4) the spinet harzburgite layer (120-200 km);5) the garnet peridotite layer (>200km).An oceanic geotherm for the upper mantle beneath Northeast China has been deduced from the calculated result by geothermometry. Compared with the typical craton geotherm, the low-velocity zone is at higher level and the oceanic geotherm nature indicate a condition for the upper mantle beneath Northeast China is "overheat". We suggest this is an interior cause of the continental rift generation in Cenozoic Era. Understandingthe composition, structure and thermal condition much better constrain the geophysical and petrological model of the upper mantle.