The　heat　dissipation　design　is　very　important　for　controller　chip.　But　the　traditional　methods　can　not　get　the　best　results.　This　paper　introduces　the　basic　theory　about　the　heat　dissipation　design　and　puts　forward　an　optimized　method　of　the　heat　sink　design.　This　paper　uses　the　thermodynamic　principle　and　matlab　simulation　to　determine　the　geometrical　size　of　heat　sink　which　can　make　the　controller　chip　work　on　the　50°C　environmental　temperature　and　the　inner　temperature　of　chip　under　150°C.　Using　this　method　we　can　design　the　heat　sink　quickly　and　efficiently,　and　realize　a　balance　between　the　performance　and　cost.　©　(2014)　Trans　Tech　Publications,　Switzerland.