Adapt to the functional integration requirements for secondary equipment in new generation smart substation, intelligent terminal units incorporated with control and protection functions are researched. Combined with project application of bay and process layer equipment, the standardization of interface, function integration, information sharing, the plug and play of whole device, software and hardware integration and reliability design of intelligent terminal are studied. Depending on architecture of hierarchical protection system in new generation smart substation, a design scheme of integrated device is given, which could realize functional autonomy in interval. The function of merging unit, intelligent terminal, measurement and control, as well as protection are integrated in one device using multiple CPU information fusion and high-speed interactive technology. Based on the compact design, the intelligent terminal unit incorporated with control and protection functions is developed, which is suitable for the 220 kV line interval. Through the test verification, it shows the proposal could effectively reduce the number of secondary equipment and simplify the system architecture of smart substation.