An accurate network topology is important to network performance monitoring, configuration management, and fault locating. However, due to the rapid development of network technology, the traditional IPv4 topology discovery method can't satisfy the needs of network management any more. Moreover, many kinds of IPv4&IPv6 transition mechanism deployed in the network bring huge challenge to network topology discovery. Therefore, in this paper, the existing methods of network topology discovery are analyzed firstly, and then an object-oriented distributed model for topology discovery in large-scale and heterogeneous network is presented, which is useful to find out what transition mechanism is deployed in the IPv4&IPv6 coexisting network.