For decades, the structure of existing power grids has not changed. It is an old structure that depends heavily on fossil fuel as an energy source, and in the future, this is likely to be critical in the field of energy. To solve these problems and to make optimal use of energy resources, a new concept is proposed, called Smart Grid. Smart Grid is an electric power distribution automation system, which can provide a two-way flow of electricity and information between power plants and consumers. The Smart Grid communications infrastructure consists of different network components, such as Home Area Network (HAN), Neighborhood Area Network (NAN) and Wide Area Network (WAN). Achieving the required level of reliability in the transmission of information to all sections, including the HAN, is one of the main objectives in the design and implementation of Smart Grid. This study offers a routing protocol by considering the parameters and constraints of HAN, which, by improving AODV routing protocol, achieves the level of required reliability for data transmission in this network. These improvements include: making table-driven AODV routing protocol, extending the routing protocol to compute multiple paths in a route discovery, simplification and providing the effect of HAN parameters. The results of the NS2 simulation indicate that applying this improved routing protocol in the HAN, satisfies the required level of reliability of the network, which is over 98%.