Smart distribution grid needs data communication systems as a support to complete their important functions. The smart distribution grid of the data and information are increasingly adopting internet protocol and Ethernet technology. Smart distribution grid equipment will be more and more within the zone have IP addresses. The current IPv4 protocol occupies a dominant position; therefore, smart distribution grid data communication systems faced with the evolution to IPv6 and network security challenges. The importance of data communications network and its main bearer of business were described. The data communications network from IPv4 to IPv6 evolution of the five processes and four stages of the transition were analysed. The smart distribution grid data communications network security imperilment and their offensive and defensive types were discussed. And the data communications network security architecture was established. It covers three dimensions, the security level, the communications network security engineering and the communications network security management. The security architecture safeguards the smart distribution grid data communication systems to IPv6 smoothly evolution.