learn about which servers are deployed in the organization network and who is scanning the networkIt network and security administrators. The novel service discovery method based on NetFlow is presented in thispaper. The six heuristics are defined to reassemble unidirectional NetFlow flows into connection一oriented bidirectional flows，and then the three types of flow are analyzed to output，so the four types of endpoints are extracted fromthree types of flow. And these six heuristics on the flow dataset are evaluated on a large campus network，and theresults of evaluation show that this approach provides a simple and efficient solution to gain visibility in organizationnetworks.