Abstract: using Morlet wavelet transform, this paper analyses the multiple time-scale variations of precipitation from 1960-2009 in Ruoergai.It inspects the true or false of the precipitation characteristics with Yamamoto method.The result shows that the precipitation of Ruoergai contains periodic movement and evolutive characteristic with various time-scale.And the precipitation of Ruoergai trends to lower in the next 2 or 3 years.A Zero of wavelet transform coefficient is not necessarily a precipitation.And that of the 16 time-scale wavelet transform of Ruoergai precipitation appeared in 1968, 1984, 2000 and 2005.