Business processes reengineering is a hotspot problem on management domain currently , how to identify enterprise processes in anfractuous enterprise system is chiefly precondition of implementing BPR. This paper ana2 lyzes the importance of enterprise processes identification on the base of studying business processes reengineering. Enterprise processes are made up of activities , and the interaction and interrelation between activies form enterprise processes system. Therefore , this paper put forward the method of enterprise avtivities identification based on CIMOSA firstly. Subsequently , the processes identification arithmetic and how to make certain the relationship of processes are provided. At last , a case to validate the arithmetic is provided.