Abstract: Based on the data of rainfall in Xi’an and the number of sunspots during the period from 1960 to 2007, a time series of precipitation was analyzed using the simple linear regression and Mann-Kendall test as well as other statistical methods. The wavelet analysis was used to study the relationship between the number of sunspots and rainfall in summer and autumn. The results showed that the proportion of rainfall in summer and autumn  was about 80% of annual precipitation in Xi’an. Rainfall in Xi’an in summer was in an increase trend, but that in autumn was in a decrease trend. Precipitation in Xi’an was closely related to the number of sunspots, and the maximum value of precipitation occurred when the maximum number of sunspots occurred or around 2 years. There was a 10-year periodic fluctuation of rainfall in summer, and also a 9-year periodic fluctuation of rainfall in autumn. There was a high correlation between the number of sunspots and precipitation at 9-year scale, a positive correlation between rainfall in summer and the number of sunspots with one or two-year difference, but a negative one between rainfall in autumn and the number of sunspots with one or two-year ahead of time.

Key words: precipitation, sunspot, periodic fluctuation, Xi^,an