Abstract: Based on the annual precipitation data from 1962 to 2012 in Chongqing, by taking the standard deviation method of means, a classification of precipitation containing 5 levels is set up, namely, the dry years, the slightly dry years, the normal years, the slightly wet years and the wet years. Take each autocorrelation coefficient as the weight number, the weighted Markov chain was used to calculate the yearly amount of precipitation of Chongqing in 2012, and the confirmatory test finds that the results thus worked out is consistent with the actual condition. The error between the value of forecasted amount of Precipitation and the value gained by actual measurement is 7.9%, which proves the validity of the said method. By adopting the ergodic theorem of the Markov chain, the limit distribution for the annual amount of precipitation in Chongqing for the recent 50 years is calculated, whose results indicate the possibility of the annual amount of precipitation in Chongqing falls most probably into the range of being a normal year with a recurrence period of about 2.9 years