中文摘要：

为了明确西北地区耕地等别分布特征及在全国耕地等别中的整体水平，以西北5省（区）农用地分等国家级汇总成果为基础，分析了西北地区耕地等别数量特点、耕地等别空间分异特征和耕地质量的影响因素。结果表明：西北地区中、低等地分布广泛，面积比例高达93．04％，耕地平均等别比全国平均等别9．8等低2．1个等别；西北地区各自然质量等地和利用等地分布的总体趋势基本一致，高等地主要分布在陕西（60．82％和86．48％），中等地主要分布在新疆（50．99％和50．54％），低等地主要分布在甘肃和陕西（53．4％、31．76％和46．87％、26．31％），青海和宁夏耕地面积较小，且以中低等地为主；各经济等地分布略有不同，即高等地主要分布在新疆（85．12％），中等地主要分布在新疆和陕西（60．86％和26．98％），低等地主要分布在甘肃和陕西（48．95％和30．74％），青海省以低等地为主，宁夏以中低等地面积比例较大；西北地区耕地质量主要受到地貌结构、土壤条件和农田基本建设3类因素的影响，且各类影响因素在西北各省域内的分布差别主要决定于各省（区）主导因素的差异，从而进一步控制西北地区耕地质量的空间分布规律。

英文摘要：

In order to evaluate the distribution characteristics of the arable lands in Northwest China and its status in the whole country ,based on the accomplishments of cultivated land classification at the national level for the five provinces in Northwest China ,the quantitative and grade and spatial distribution characteristics of the arable lands were analyzed in Northwest China ,as well as the influential factors on land qualities .The results showed that medium and low grade lands were broadly distributed ,up to 93 .04% of the area .The average arable grade was 11 .9 ,2 .1 lower than the national average level （9 .8） .The distribution of arable land natural quality and utilization grade were roughly the same in Northwest China .High-grade arable lands were mainly in Shaanxi ,medium-grade arable lands were mainly in Xin-jiang ,and low-grade arable lands were mainly in Gansu and Shaanxi .Arable land area in Qinghai and Ningxia were small ,majority of which was medium or low-grade .In addition ,the distributions of arable land economic grade were slightly different .High-grade arable lands were mainly in Xinjiang ,medium-grade arable lands were mainly in Xinjiang and Shaanxi ,and low-grade arable lands were mainly in Gansu and Shaanxi .Qinghai had large area of low-grade arable lands ,and Ningxia had large area of lower-grade lands .The arable land quality of Northwest China was mainly influ-enced by geomorphological structure ,soil conditions and basic farmland constructions .Factors that influenced the varia-tions in spatial distributions in different provinces were mainly determined by different dominant factors of the provinces , which further controlled the spatial distribution characteristics of the arable land quality in Northwest China .