Abstract: The workflow merging requirements are formally described through relationship-rules and activity-rules. Moreover, an algorithm to check conflicts in the merging rule set is proposed based on the reachability relationships. This algorithm can find out combinations of conflict merging rules from the given rule set through tracing new reachability relationships and corresponding deriving rules, which provides the basis for the adjustment of the merging rule set. Concrete example analysis shows the effectiveness of the proposed algorithm. This research provides support for the successful deployment of workflow merging.