Network topology discovery is important for many key network management tasks. However, as the network scale expands, the network structure gets complex. The previous SNMP-based network topology discovery algorithms cannot effectively identify subnet types and multi-IP devices, and they have low topology efficiency and accuracy. In view of the above problems, this study proposes an SNMP-based topology enhancement identification (SNMP-TEI) algorithm. Firstly, the subnet IP address is heuristically determined, and probes are sent to it, so as to judge the subnet type according to the detection results. In addition, probe injection is stopped in a timely manner after the subnet type is determined, so as to prevent the network load from being too large. Secondly, the device fingerprint is set through system information recorded by MIB-II, and a device type identification algorithm is used to identify the device fingerprint of the terminal host IP, so as to identify multi-IP devices. The experimental results show that this method can effectively identify subnets and multi-IP devices in simulated networks and reduce the network load, with a detection accuracy of 96.43%.