To quantitatively differentiate the contributions of climate and human being to vegetation variation on the northwest of loess plateau is significant to the ongoing vegetation restoration projects.This paper puts forward a method of detrended regression residuals methodto eliminate the effect of a common trend.First use the trend-eliminated data of plants and climate to construct regression model and then use the original climate data to simulate the plants and conduct residual analysis.The spot vegetation NDVI based on the experiments of time series shows that,thedetrended regression residuals method is superior to the conventional methods.The recent 15-year vegetation on the northwestern loess plateau activity has been generally bettering,due to a human contribution rate of 92%and a climate contribution of 8%.Meanwhile,the two effects showed great spatial heterogeneity.