Grid system has facilitated large scale, flexible, distributed, secure and coordinated resource sharing. It aims to make full use of the network resources and build a harmonious collaborative community. However, resource management and quick resource location are still urgent problems for grid systems, especially under large, dynamic environment. This paper presents SIKA a grid-based overlay network for knowledge grid system. It groups the nodes into domain sensitive communities, but by defining new inter community organization mechanism, it successfully avoids using super peers. The main characteristics of this architecture are highlighted by its convenience for community analysis, promising scalability, its search efficiency, as well as its robustness. The experimental performance results presented here demonstrate the efficiency of the design.