Several　means　of　tongue　manifestation　information　fusion　are　analyzed　and　compared　and　the　means　based　on　feature　layer　and　decision　layer　and　both　are　available　in　principle.　The　experiment　results　show　the　correct　recognition　rate　based　on　them　is　low.　It　is　very　difficult　to　acquire　a　good　result　because　of　some　factors　such　as　much　difference　between　two　features.　Rough　set　theory　is　a　valid　means　to　solve　this　problem.　Some　symptoms　may　be　defined　by　the　tongue　manifestation　features　and　some　symptoms　cannot　be　defined　by　the　means　based　on　the　rough　set　theory,　which　avoids　the　error　judgement　in　some　sense　and　is　crucial　to　the　Chinese　medical　diagnosis.　Rough　set　theory　is　hopeful　to　become　an　important　means　in　the　standardization　of　the　symptom　of　Traditional　Chinese　Medicine　(TCM).