Global warming caused by greenhouse gas emissions has had a profound impact on human survival and development. Consequently, this phenomenon has received widespread attention from the international community. Vegetation can absorb greenhouse gases CO2 , and has a huge carbon sink function, so it has an irreplaceable role in slowing global warming. The carbon sink capacity of vegetation has a significant impact on regional and global climate change. Carbon emissions are undoubtedly enormous in the mid and high latitudes of the Northern Hemisphere, so studies on terrestrial ecosystem carbon dynamics and spatial patterns in the arid region of northwest China may provide an accurate assessment how China contributes towards mitigating global climate change and CO2 emission reduction. The net primary productivity (NPP) and heterotrophic respiration (RH) in the arid region of northwest China were calculated by using MODIS images, meteorological data, and a vegetation type map, in combination with an improved CASA model and soil microbial respiration model. The NPP and RH were then used to estimate net ecosystem productivity (NEP) and vegetation carbon sink from 2001 to 2012. Spatial-temporal characteristics and the reasons for NPP and carbon sink variation in the arid region of northwest China were analyzed. The results show that research methods used in this paper were able to quickly extract ecosystem net primary productivity and carbon sink for the northwest arid region. The methods used are efficient, convenient, and practical for large scale carbon balance and carbon cycling studies in this region. Comparison indicated small gaps between simulated and measured site values. The overall difference in the spatial distribution between simulated values and MODIS NPP products is also small, and the volatility of the analog value is less than the value of MODIS NPP products. NPP in the study area showed strong seasonal variation. The maximal NPP value was obtained in July, while the minimum value was obtained in December. In the 12 study years, annual averages of NPP changed minimally. Average carbon sinks showed fluctuating in the 12 years, but increased in general, overall. The carbon sink mean changed from a minimum of 609.04 gC-1 m-2 a-1 in 2006 to a maximum of 648.02 gC-1 m-2 a-1 in 2012. The change in mean carbon sink was less than 39 gC-1 m-2 a-1 , with a standard deviation of 11.68. Annual maximum carbon mainly occurred in May, June, and July. Carbon sink fluctuated, but showed an overall upward trend in the northwest arid region between 2001 and 2012. Carbon sink in this region gradually increased from West to East, with Eastern >West >Central. The carbon sink capacity of different natural areas was quite different. The largest carbon sink capacity was recorded in the grassland area of West Liaohe River Basin, while the smallest was recorded in the warm temperate desert region of the Tarim Basin. The annual maximum carbon sink mainly occurred from May to July. Carbon sink was ranked in the order of coniferous forest>farmland> shrubs > broad-leaved forest > grassland > desert steppe.%通过修正的CASA模型估算2001—2012年间西北干旱区陆地生态系统的净第一性生产力(NPP),并结合土壤微生物呼吸方程,计算出12a的净生态系统生产力(NEP),分析了植被碳汇的时空变化规律。结果表明：研究区的NPP表现出很强的随季节变化的规律,全年7月份NPP为最高值,12月为最低值,12年间NPP的年均值变化不大。2001—2012年研究区的植被碳汇在波动变化中有所增加,其中2006年的碳汇平均值最小,为609.04 gC m-2 a-1,2012年最大,为648.02 gC m-2 a-1；年内碳汇的最大值主要出现在5—7月；碳汇能力由大到小的植被类型为针叶林>农田>灌丛>阔叶林>草原>荒漠草原。研究区多年平均碳汇量呈现自西向东逐渐增加的规律,西辽河流域草原区的NPP和碳汇平均值最大,塔里木盆地暖温带荒漠区最小。
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