This paper addresses the problem of managing variance in process instances for business process modeling. In business work practice, variance is a valuable source of organizational intellectual capital that needs to be captured and capitalized as it represents a preferred and successful work practice. Therefore, it is important to provide an effective method to analyze the similarity between these variants since it can bring benefits for organization productivity and provide consistency. Through this paper, we propose a systematic approach to deal with the complexity of business process variants by analyzing the structure relationship and the execution construct in order to measure the similarity degree of the variants.