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.