Abstract: Due to defects of traditional discovery in networking protocol, this paper analyzes methods of traditional network protocol analysis, vulnerability types, causes and discovery approaches, and disadvantages of traditional network protocol discovery. Thus, this paper proposes a design plan of automatic analysis and discovery tool based on integration of automatic protocol analysis technology, trafifc clustering sorting algorithm, deep packet inspection technique and Fuzz. This paper designs a set of vulnerability discovery system for automatic protocol, which provides systematic working procedure and structure, and function of each module and their interrelations;and finally gives a system model realization, based on which vulnerability discovery is conducted to the FTP server software to verify validity and efifciency of the system design plan. The major innovation of this paper is the integration of automatic protocol analysis technology, trafifc clustering sorting algorithm and DPI technology, which forms the network protocol vulnerability discovery technology that can conduct automatic protocol analysis and generate test path automatically.