Software designers usually overlook Analysis Model Because of its complexity, and make Design Model directly from Use Case Model. But this method cannot verify the accuracy of the use cases. This paper presents a modeling method of firstly from Use Case Model to Analysis Model, then mapping Analysis Model to Design Model, and describes the principle of this method, explains specifically how to distinguish Analysis Class from Use Case Model, and discusses deeply how to obtain the attributes of Entity Class and how to design the operations of Analysis Class.