Agent-based modeling and simulation technology is considered to be an effective way to study complex systems, Repast Simphony platform provides favorable conditions for agent-based modeling and simulation. According to the problem of how to build simulation models of complex systems on Repast Simphony, this paper focuses on Repast Simphony simulation platform. Its technical superiorities is introduced. The similar simulation platforms are analyzed comparatively. The general simulation and modeling process is summarized through analyzing the main library for the platform. At last, an improved Schelling model simulation example is given for further describing the design and implementation for building complex systems based on Repast Simphony. It is of significance to use Repast Simphony for agent-based modeling and simulation research.