Under the background of global change,distinguishing the impact of human activities and climate fluctuation quantitatively is of great significance to vegetation growth in the arid regions. In this paper,using a variety of statistical methods,the spatial and temporal variation characteristics of the land use /cover change ( LUCC) from 1990 through 2010 and the normalized difference index ( NDVI) from 1982 through 2010 in the arid regions of Northwest China are analyzed,and the LUCC effects on NDCC change are quantitatively evaluated. The results are as follows: ( 1) One of the fastest growth was arable land,up to 13 476 km~2,followed by forest lands and waters; the area increased mainly from grassplot ( 12 590 km~2 ) and unused land ( 6 025 km~2 ) from 1990 to 2000. ( 2) The rate of change of various land types were as follows: arable land > construction land > waters > woodland > grassplot > unused land. ( 3) The land-using degree index ( 0.79) in the study area from 2000 to 2010 was significantly higher than it from 1990 to 2000 ( 0.23) ,showing that the influence of human activities on land use has markedly enhanced in recent years. ( 4) The NDVI had increased from 1982 to 2010, but in recent years ( 2002 - 2010) it had decreased slightly. Specifically,the contribution of LUCC on NDVI had been relatively low from 1990 to 2000,only 2.9%; even so,the contribution from 1990 to 2010 had been 26.7%,showing the contribution of climate change on vegetation index change up to 73.3%.