SCUC is advanced optimization software which has been well used in power generation and dispatch around the world. This paper briefly introduces the evolutionary background of SCUC. The mathematical model and algorithms of SCUC are presented and analyzed. Based on the mixed-integer programming method， SCUC optimization software is developed. A large-scale system of 500 units is tested based on the IEEE RTS system. And an actual provincial system in China including 161 units and 109 network constraints is examined as well. The results show the validity and practicability of the algorithm and software.