Revealing the influence characteristics of precipitation distribution on desert vegetation is helpful for understanding the process of vegetation cover change in arid area under the background of global climate change. Spatio-temporal pattern of Normalized Difference Vegetation Index (NDVI) and its possible relations to precipitation in the northern piedmonts of the Tianshan Mountains were analyzed based on MODIS 1B data and daily precipitation data in 1999-2014 from 7 meteorological stations. The results show that there are regular characteristics in the NDVI responding to precipitation at different time and spatial scales in the growing season. The lags of NDVI responding to precipitation become less and less obvious over time. The correlation between daily precipitation and NDVI increases firstly, then decreases, and reaches the maximum value in the medium term of the growing season. Lag of NDVI is clearly related to the precipitation of the region. The annual NDVI of each region is also different. When dry length is over 18 days, the significant effect on NDVI can be found. Overall, whether the annual precipitation in the study region is large or small, the vegetation all brings out essentially unchanged or slight improvement tendency during periods of heavy precipitation in growing season. Conversely, it all brings out degradation tendency or essentially unchanged (the slope of the trend is a negative relative minimum) during periods of little precipitation. Therefore, it can be estimated by the exploration of vegetation changes how dry and wet of atmosphere. Furthermore, precipitation and distribution type have obvious influence on NDVI. Precipitation of 6.1-12.0 mm is the most favorable condition for the growth of desert vegetation, and it can increase NDVI by more than 0.15. B type (referring to two consecutive days of precipitation, and precipitation on the first day more than next day) and A type (referring to two consecutive days of precipitation, and precipitation on the first day less than next day) respectively are the best distribution types of rainfall in the early and middle of the growing season. Exploration of the response pattern of NDVI to precipitation can not only offer a scientific basis for rational irrigation and water conservation, but it can also provide important theoretical guidance for restoration of damaged ecosystem in northern piedmonts of the Tianshan Mountains.