As the foundation of network management technology, Network topology has been always the research hotspot which reflects the basic characteristic of a network, so from its topology, you can figure out the bottleneck and hidden security problems of a network easily and quickly. The technology of network topology visualization is such a technique that it researches on network topology by discovering, monitoring and displaying it. A network topology visualization system which is based on this technology can help network manager realize and manage the network more convenient. In this paper, we will mainly introduce two popular algorithms--network topology discovery algorithm on the base of SNMP protocol and network topology discovery algorithm on the base of ICMP protocol. Combining with the practical environment of the target network which the system will run on, we design a more suitable program for this network. We firstly research on the structure of network's topology and its model combining with the feature of the target network, and then make use of Flash technology which shows huge advantages on graphic processing and portability, further more its Action Script programming language is very suitable for dynamic graphical development. Thus in this paper, Flash Action Script technology will be used in the development of system's user interface after we solved the difficulties of dynamic interaction between Flash and database, real-time problems.