Using monthly precipitation records from 122 meteorological stations in the arid region of Northwest China, the spatial and temporal distribution of precipitation were analyzed for the period 1961-2011. The Mann-Kendall trend test and Morlet wavelet analysis were utilized to detect the spatio-temporal distribution of the mean annual and seasonal precipitation. In the present paper, the Northwest arid area was divided into the northern Xinjiang region, the southern Xinjiang region, Qilian Mountains, Tianshan Mountains, Hexi Corridor region, and the Inner Mongolia Plateau region. The results obtained indicate that the mean annual precipitation (MAP) in the northwest arid region had a significant rising trend (P < 0.01), at a rate of 9.31 mm/decade. The mean annual precipitation in the Qilian Mountains area rose the fastest, increasing by 38.67 mm/decade; the second fastest was on the Tianshan Mountains, increasing by 16.79 mm/decade; the slowest increase was in the Hexi Corridor, southern Xinjiang, and western Inner Mongolia, increasing by 8.49 mm/decade, 5.44mm/decade, and 5.09 mm/decade, respectively. The Mann-Kendall test showed that the increasing trend of the mean annual precipitation in each area was statistically significant at P < 0.05 level, except in western Inner Mongolia. A rising tendency of the mean annual precipitation was observed in 95.9% of the stations in the study region, but the amplitude shows regional differences. The Tianshan Mountains, Qilian Mountains, and northern Xinjiang show a rising tendency in all stations, followed by those in southern Xinjiang and the Hexi Corridor, whereas the lowest increase is in western Inner Mongolia, accounting for 77.78% of the stations. Centers of the highest increase in mean annual precipitation were identified. for example, Yeniugou (52.5 mm/decade) in the Qilian Mountains, Tianchi (22.8 mm/decade) in the middle of the Tianshan Mountains, and Xinyuan (28.3 mm/decade) west of the Tianshan Mountains. There are seasonal differences in the rising trend of the mean annual precipitation. The rate of precipitation increased the fastest in spring, by 3.32 mm/decade, followed by the rate in summer and winter, by 5.44 mm/decade and 5.09 mm/decade, respectively, whereas it is the slowest in fall (only 2.07 mm/decade). The precipitation rate in winter was universal across the studied region, it was 98.36% in all stations. Summer precipitation rate presented regional differences; the precipitation rate was 79.51%. Abrupt changes in mean precipitation in the arid region and sub-region of northwest China are evident. The changes occurred in northern and southern Xinjiang and western Inner Mongolia in the middle of the 1980s, in the Hexi Corridor and the Qilian Mountains changes occurred in the middle of the 1970s, and in the Tianshan Mountains the changes occurred in 1991. The abrupt changes in the mean precipitation in each area were statistically signicant at P < 0.05 level. The Morlet wavelet analysis showed that the precipitation has an approximate 4-year, 8-year, 12-year, and 22-year cycle in the studied region. According to the level of wet and dry, the rates for normal, abnormally dry, dry, wet, and extremely wet mean precipitation series were 32%, 12%, 24%, 16%, and 16%, respectively. Since the 1980s, precipitation has increased significantly; the rate of positive anomalous years has increased from 10% in the 1970s to 80% nowadays. Today, it is relatively wetter in the arid region of northwest China, with an obvious ongoing increasing trend.