Abstract: Observational day and night precipitation data from 89 stations in Xinjiang province during 1961-2005 were used to assess the temporal and spatial changes in daytime and nighttime precipitation processes. The goal of this investigation is to understand the change characteristics and trends of the precipitation process in both the daytime and nighttime in this area, under a background of increasing annual precipitation. The results show that the multi-year average of annual precipitation at nighttime was larger than at daytime during 1961-2005 and that precipitation increased significantly in both the day and the night. The increasing trend of precipitation is larger in the nighttime than in the daytime, with the annual increasing trend in the daytime and nighttime respectively accounting for 49% and 51% of the total increasing trend in annual precipitation. In addition, there are significant regional differences between southern and northern Xinjiang. The amounts of daytime and nighttime precipitation both show significant jumps, but at different times: In 1986 for the daytime, and in 1991 for nighttime precipitation. Further, the annual number of rainy days during the daytime is less than it is at nighttime, although they both show a clear increasing trend. This trend of increasing rainy days is greater for daytime precipitation than it is for the nighttime. Precipitation intensity in the daytime and nighttime also show a significant increase, with both precipitation intensity and the growth rate of precipitation intensity being greater at night than they are during the day. The increase in the number of rainy days is the main cause of the total increase in precipitation, while changes in precipitation intensity have little influence on the total. Meanwhile, the annual number of drizzle days show a distinct decrease in both the daytime and the nighttime. Drizzle days during the daytime are greater than at nighttime, and the decreasing rate is the same between day and night. Finally, the numbers of heavy precipitation days and their intensity both show an increasing trend. The daytime and nighttime heavy precipitation has a significant correlation with their respective total precipitation amounts, thus, heavy precipitation has a considerable influence on total precipitation. Further study is required to establish the causes of these differences in precipitation change characteristics between the daytime and nighttime.