Abstract: Based on daily precipitation data at 14 meteorological stations in the Sanjiangyuan region during winter period (from October to April) from 1961 to 2017,the spatiotemporal characteristics of precipitation and an extreme snowfall index defined by a percentile threshold method were analyzed,using some statistical methods such as the linear tendency analysis,the Mane-Kendal trend test,and the Morlet wavelet analysis.The results show that there is a significant increase in precipitation over the Sanjiangyuan region during winter period.The extreme snowfall threshold varies between 2.6 and 7.8 mm with an occurrence frequency ranging from 1.6 to 3.8 d.It also exhibits an increasing distribution from the northwestern region to the southeastern region,with the high-value center located in the Qingshui River and low-value center in Xinghai.The extreme snowfall increases significantly by 2.2 mm/10 a with a distinct abrupt change in 1993 and has an obvious quasi-periodic cycle of 12 a.The extreme snowfall mostly occurs in April and October,and the regions with a higher occurrence frequency of snow disaster are located in the middle and southern areas (centers located in Qingshui River and Zaduo) with a higher occurrence probability of moderate snow disasteron