With the continuous development of information technology
the use of metropolitan area networks is becoming more and more common
but the problems related to metropolitan area networks are too much
and the first is the network security problem.Aiming at this phenomenon
this paper conducts a research on metropolitan area network planning and design based on network security.It mainly starts from the concept of metropolitan area network and outlines how to improve the security of metropolitan area network by building a secure and standardized metropolitan area network.