The power grid storm disaster monitoring system involves power system data，geomagnetic data, satellite data and other earth space observation data. To solve such problems as the system's large quantity of data, storage and processing difficulties, using cloud computing in the system is putting forward. The basic concepts and the services of cloud computing are introduced first. From the aspects of the front-end data collection and communication methods to the background software data processing, the GIC (geomagnetically-induced current) monitoring system is showed. Then the issues of the continuous expansion of the system are analyzed in detail. The architecture of the power grid storm disaster monitoring system based on cloud computing is given. Security problem of implementation of the system using cloud computing technology are finally discussed.