Abstract: This paper presents the principle and testing method to the precipitation processes predicted by the 150 days' cycle. The precipitation processes predicted by the 150 days' cycle method from 2002 to 2012 were assessed qualitatively, and it presented an average score of 67.3, the vacancy forecast rate is 5.9% and the missing forecast rate is 26.8%. The framework of the prediction system for precipitation processes within a month was introduced. The system has eight major function parts, system introduction, NC data processing, data call, analysis and calculation, prediction conclusion making, assessment data management, production issue, and system settings. This system can calculate the similarity coefficiency, historical coverage rate and the historical evolution accuracy, vacancy or missing process. The quantitative application of the method was improved by the system.