In this paper, a software design improvement approach through anti-pattern identification by case based reasoning is proposed to improve software quality and maintainability. First of all, XML based design template at micro-architecture level is presented to formally define patterns and anti-patterns. Secondly, according to 4R model of CBR, the retrieve, revision, reuse and retaining of design improving cases are illustrated. Especially, similarity measurement methods of class diagrams, sequence diagrams, OO quality metric facts and semantic constraints are proposed to identify problematic inflexible anti-patterns and replace them with high quality design. Finally, the architecture of refactoring environment developed to support this approach is introduced.