This paper aims to provide a complete theoretical analysis for the creative methods. First, the feature set is used to express the creative solution, and some of the basic operators induced from different creative methods are defined. Next, the paper employs the information entropy theory to prove the usability of the creative method to produce creative solutions, and presents a detailed proof of the creating ability of the methods in an evolving framework. The prime contribution here is that the paper provides not only the theoretical foundation for the creative methods, but also the way and theoretical foundation for implementation of the system of creative design. Finally, an empirical study demonstrates that solutions, which meet the proposed theory, tend to score high on creativity evaluation by field experts.