Abstract: To study the dynamic behavior and rule of the transition between drought and wetness in North China,a method is put forward to set up the dynamic mode about precipitation at one specific level of climate by use of the Climate Levels theory,the wavelet analyses and the technique of setting up model according to catastrophic points. Then,this method is adopted to analyze the precipitation data of many stations in North China and set up a dynamic mode of chronological level change. In the end the mode is used to reveal the characteristics of the precipitation in this area in the sight of dynamics. The result of the research demonstrates that for most stations in this area,the phases of drought are longer than that of wetness. The former can last over twenty years while the latter can only last less than ten years. Long drought phases and short wetness phases are the main characteristics of North China.