Global climate change is more and more serious for drought and affect for agricultural production in Semi-arid Area of the West region of Heilongjiang Province. So, steady progression of agricultural production impose challenge in this area. In order to solve above-mentioned problems, the authors took Gannan county as example, analyzed the multi-time scales variation characteristics and jump characteristics of actual growing seasons precipitation time series in Gannan county through using the wavelet theory, and the main periods of growing season precipitation change and variation trend of drought-flood in this area were revealed. The study can provide scientific gist for fully utilizing natural precipitation and exploiting maize water potential productivity in Gannan county so much as the entire Area of the West region of Heilongjiang Province.