With the rapid development of computer networks, network management has become more and more complex. In order to improve the operational and intelligence of the management of network equipment and services, we present an improved network topology auto-discovery algorithm based on Simple Network Management Protocol(SNMP), Internet Control Message Protocol(ICMP) and Address Resolution Protocol(ARP). The algorithm based on standard MIB-II and ICMP command, according to TCP/IP protocol addressing relevant principles, to achieve rapid network topology discovery and further reduce the network load. Experimental results show that the algorithm can quickly and accurately find the network topology.