To set up a reasonable crop irrigation system in the context of global climate change in Northern Xinjiang, China, reference crop evapotranspiration (ET 0 ) was analyzed by means of spatiotemporal variations. The ET 0 values from 1962 to 2010 were calculated by Penman-Monteith formula, based on meteorological data of 22 meteorological observation stations in the study area. The spatiotemporal variations of ET 0 were analyzed by Mann-Kendall test, Morlet wavelet analysis, and ArcGIS spatial analysis. The results showed that regional average ET 0 had a decreasing trend and there was an abrupt change around 1983. The trend of regional average ET 0 had a primary period about 28 years, in which there were five alternating stages (high-low-high-low-high). From the standpoint of spatial scale, ET 0 gradually increased from the northeast and southwest toward the middle; the southeast and west had slightly greater variation, with significant regional differences. From April to October, the ET 0 distribution significantly influenced the distribution characteristic of annual ET 0 . Among them sunshine hours and wind speed were two of principal climate factors affecting ET 0
