Compared with other large-scale warfare simulation systems, wargame, as a traditional type of warfare simulation, has the advantages of low cost, convenience, practicability, etc. This paper discusses the system structure and class model based on "Future: Korea War" which is a product of U.S. "One Small Step" company's Millennium Wars series strategic-level wargames, and designs wargame umpire rule description method based on CLIPS. The "Future: Korea War" system umpire rules could be revised without recompilation of the application software, which enhances the flexibility and expansibility of the wargame umpire rules.