Understanding changes in vegetation productivity and carbon use efficiency and their responses to climate change is significant to accurately assess and predict regional carbon budget in Northeast forest area,a region being an important carbon sink and sensitive to global change.Based on MODIS monitoring data and vegetation type distribution data,I analyzed the spatiotemporal variations of ecosystem productivity (net primary productivity (NPP),gross primary productivity(GPP)) and carbon use efficiency (NPP /GPP) of Northeast forest from 2000 to 2015.Results showed that the average NPP and GPP were 346.4 and 773 g C·m~(-2)·a~(-1),respectively,and the average NPP /GPP was 0.45 during 2000 and 2015.NPP and GPP of different forest types were following the order:coniferous and broad-leaved mixed forests >deciduous broad-leaved forests >coniferous forests,while the difference in NPP /GPP was not significant among different forest types.NPP and GPP were high in Southeast part and low in Northwest part.From 2000 to 2015,the NPP,GPP and NPP /GPP of Northeast forest showed a fluctuating increase,suggesting the carbon sequestration capacity was gradually enhanced.However,the trends and rates of NPP,GPP and NPP /GPP showed spatial variation.NPP,GPP and NPP /GPP increased significantly in the southern part of the Daxing'anling while decreased significantly in the northern part of the Daxing'anling,and showed a weak increasing trend in the rest of Northeast forest.The increase of annual precipitation was the main factor driving the fluctuating increase of NPP,GPP and NPP /GPP in Northeast forest.