Abstract：At present, the process layer networking process of smart substation is constantly advancing, but there is no quantitative method to evaluate the transmission reliability of the process layer network of smart station. In order to improve the standardization and reliability of smart station networking, it is urgent to put forward a complete set of reliability evaluation methods for the process layer network. The reliability evaluation method includes several key evaluation indicators. Based on each evaluation indicator, different weight values are assigned to the influence degree of network reliability to objectively evaluate the security and reliability of network data transmission under various networking architectures. It is necessary to consider the technical and economic factors of each voltage level to realize the optimal selection of network scheme.