Abstract: In order to process alarm information of power grid rapidly, efficiently and intelligently, an intelligent alarm system of power grid is developed based on Multiagent and expert system. The rules to process alarm information are studied based on Rough set and Decision tree, and the expert system of processing alarm information is constructed based on knowledge base that composes of these rules to intelligently analyze alarm information, such as noise filtering and reasoning. The alarm information processing is divided into multiple agents by Multiagent technique, and the cooperation of Multiagent, data sharing and mechanism of communication are studied, then alarm information processing can become rapid and efficient. The system has been applied in Dingxi power grid of Gansu province, and operation effect verifies the practicability and validity.