This paper describes the concept of workflow merge and methods for merging business processes. We append effect annotations to activities of business process, use RPSTs divided the process graph to fragments then accumulate these effects according to these SESE fragments, detect exact clone and approximate clone between the two process models, finally design a merging algorithm to consolidate two processes. It is shown that to avoid invalid merges, one choose merge unit is SESE fragments, we also raise issues of more complex merge problems, such as semantic annotations.