In order to build up intelligent power dispatching of bulk power grid， integration of secondary system in power control center and substations needs standardized and modular secondary system construction which results in information interaction more flexible. Implementation of secondary system integration is with multi-specialty technology merging. Some key technologies including grid fundamental data enhancement， application support platform， and advanced power analysis software（PAS） for intelligent power dispatching of bulk power grid are studied. In respect of building grid fundamental data， SCADA supporting system with united time stamped measurements is designed. In respect of support platform， general solution scheme of integrated application support platform is proposed. In respect of new PAS， fast status estimation based on time stamped measurements， on-line self-adaptive defense lines， real-time pre-warning and pre-control system are put forward.