This　paper　constructs　a　tumor　growth　model　(TGM　for　short)　based　on　three-dimensional　cellular　automaton.　The　cells　of　the　TGM　are　divided　into　normal　cells　and　abnormal　cells　by　their　state　values.　The　abnormal　cells　mean　tumor　cells　and　divided　into　proliferative　cells,　non-proliferative　cells　and　necrotic　cells　by　their　state　values.　The　TGM　unifies　the　evolution　rules　of　the　normal　cells　and　abnormal　cells　including　proliferative　and　non-proliferative　cells　and　necrotic　cells.　The　cells　and　its　neighborhoods　and　evolution　rules　of　the　TGM　completely　abide　by　the　design　principle　of　standard　cellular　automata　so　that　virtual　experiment　and　analysis　on　the　TGM　can　be　carried　out　with　the　unified　theoretical　frame　of　cellular　automata.