As model analysis is the basis of the switching converter research,a switching system-based unified model is proposed according to the hybrid system theory,which is suitable for DC-AC and various types of DC-DC switching converters. Then,the construction method of Lyapunov function is proposed based on the parameter matrix of the unified model and the system switching laws are put forward by constructing this function. Meanwhile,the system stability under the proposed switching laws is analyzed and a general approach and some specific steps for the unified modeling are summarized. Finally,some simulations are carried out by establishing models for the DC-AC and three-level Buck-type DC-DC converters,and the rationality of the established models and the effectiveness of the modeling method and steps are both verified.