This paper presents a graph transformation based approach to design pattern evolution. An evolution of a design pattern includes modifications of pattern elements, such as classes, attributes, operations and relationships between classes. Compared with other techniques, graphical notation, as a natural and intuitive way in software modeling, is suitable to be used at the transformation stage. In this paper we focus on the automated evolution of design patterns using graph transformation. The rules for the potential design evolutions are defined. After the evolution process, a graph grammar based syntax parser is proposed to check the structural integrity of the evolved design patterns.