This　article　builds　a　sort　of　immune　system　model　basing　on　cellular　automata　method,　in　order　to　simulate　the　immune　response　to　tumor　growth.　This　paper　discusses　immune-tumor　system　at　the　cellular　level,　based　on　the　simple　two-dimensional　stochastic　discrete　cellular　automaton　model.　In　this　simple　three-layer　structure　designers　take　into　account　the　features　of　the　immune　response,　and　regard　many　different　kinds　of　immune　cells　as　the　single　immune　element.　The　model　describes　the　interaction　between　cancer　and　immune　cells,　and　shows　immune　cells　growth　around　tumor.　The　authors　study　the　normal　cellular　automaton　model,　and　design　the　evolution　growth　rules.　At　last　we　build　discrete　cellular　automaton　model　of　tumor-immune　system,　and　simulate　tumor-immune　system　on　computer.　The　model　predicts　the　dynamics　of　the　tumor-immune　system　in　agreement　with　Gompertz　growth.　Via　adjusting　different　parameters　of　simulating　model,　the　ultimate　results　indicate　the　basal　behaviors　of　tumor-immune　system　exactly.　©　2003　IEEE.