The communication mechanism of 4-in-1 metering system based on concentrator mode is studied, single point fault and communication bottleneck in 4-in-1 metering system are analyzed. A large scale meter management architecture based on Ad Hoc networks is put forward, in which the communication network of the smart grid is used as a virtual private network of many kinds of metering devices, and a wireless Mesh network is formed by a plurality for metering devices nearby. Based on the extended SCEP protocol and lightweight certificate, a meter authentication scheme is proposed to solve the identity authentication and security problem of multiple meter network. A data acquisition protocol based on IPv6 is designed, and prototype system tests are conducted. Results show that the key functions such as network topology discovery, data collection and so on are realized in this system. The new mechanism can significantly reduce the repetitive construction of communication network, and support the new business of " Internet plus" mode.