A distributed and parallel power system grid computing platform is developed by use of certain Internet open sources and by integrating high efficiency grid processing software GridGain into InterPSS， a power system simulation platform. The new platform， named InterPSS grid computing platform， works by gathering the idled computer hardware resources in the local area network（LAN）. Compared to the existing grid-computing platform， the proposed solution is characterized with high parallel efficiency， easy setup and maintenance， and open source， has a bright future in applications to the power system field. This conclusion is drawn on a concrete comparison between the proposed and existing solutions.