This paper designs and implements a network traffic collection and analysis system(NTCA).Network traffic is collected from multiple clients.According to the offline traffic analysis,network flows are analyzed and annotated with application protocol.At the same time,the results are stored in the system.NTCA also provides a visual interface to simplify the configuration process.With good flexibility and scalability,NTCA can be extended to a network traffic clas sification system,which is crucial to the research of network security technology.