Uneven intra-annual precipitation distribution in arid regions can intensify both drought and flood events，thereby inhibiting ecosystem functioning and water resource management. Under global warming，total precipitation in arid Northwest China（NWC）has significantly increased since the 1980s. Yet，it is insufficient to understand the spatio-temporal variations in its intra-annual distribution patterns. Based on the CN05. 1 gridded precipitation dataset，we comprehensively examined the spatio-temporal variations in the temporal homogeneity of precipitation across multiple time scales from 1961 to 2021. As revealed by the Precipitation Concentration In‐ dex（PCI）at monthly scale，NWC exhibits pronounced seasonal precipitation patterns，with an average PCI of 17. 8. From 1961 to 2021，PCI show a decreasing trend over 89. 1% areas of NWC with an overall tendency of -0. 29·（10a）-1，especially in the hyper-arid sub-region［-0. 44·（10a）-1］. The reduction in PCI is primarily attrib‐ uted to the decreasing proportion of summer precipitation［-0. 6%·（10a）-1］and the increasing proportion of win‐ ter precipitation［0. 35%·（10a）-1］，indicating a weakening seasonal concentration of intra-annual precipitation. At daily scale，the long-term changes in the Precipitation Concentration Degree （PCD） and Precipitation Concentration Period（PCP）agree with the monthly-scale PCI. PCD presents a significant decreasing trend ［-0. 008·（10a）-1］，and PCP generally varies insignificant with slight decreasing in some regions［maximum -1. 54 d·（10a）-1］. On average，50% of annual precipitation in NWC is contributed by the 11 wettest days. The wettest days contributing to half of annual precipitation decrease at a rate of -1. 8 d·（10a）-1 in humid sub-region but increase at 0. 9 d·（10a）-1 per decade in the hyper-arid sub-region. Our findings provide critical scientific in‐ sights in climate adaptation，risk mitigation and strategy making for drought and flood extremes in arid NWC.