[Objective] The vegetation cover in Xinjiang Uygur Autonomous Region from 2001 to 2017 and its response to the extreme climate index were analyzed in order to provide a theoretical basis for the ecological-environmental protection and sustainable development of the region.[Methods] Data of the MOD₁₃Q₁ normalized difference vegetation index (NDVI), temperature, and precipitation during the period from 2001 to 2017 were used along with the maximum synthesis method, Savitzky-Golay (SG) filtering method, and a correlation analysis to investigate the relationship between the NDVI and the extreme climate index during the growing season.[Results] ① The vegetation cover in Xinjiang was not high overall from 2001 to 2017, with a slowly improving trend since 2009, which is likely to continue in the future. ② In general, the NDVI decreased from northwest to the southeast. The Tianshan Mountains and Ili River valley were the areas with the highest values, and the NDVI in the sub-regions of Northern Xinjiang was generally higher than that of the Southern Xinjiang. ③ The NDVI was negatively correlated with the extreme temperature index in the central part of Northern Xinjiang and the southwest part of Southern Xinjiang. The diurnal temperature range (DTR) and number of cool nights (TN_10p) were the main influencing indices. The NDVI was negatively correlated with the average temperature index in desert areas, whereas it was positively correlated in some mountainous areas, which was mainly due to the variation of the annual average temperature (T_y). ④ The NDVI was positively correlated with the precipitation index. The maximum 1-day precipitation amount (RX_{1 d}), maximum 5-day precipitation amount (RX_{5 d}), and annual precipitation (TP_y) were the main contributors.[Conclusion] The vegetation coverage in Xinjiang is developing in a positive direction. The response of the NDVI to the precipitation index was higher than its response to the temperature index. The precipitation index mainly exhibited a positive influence, while the temperature index had a negative influence. Precipitation had an obvious promoting effect on the improvement of vegetation in Xinjiang.