A　sol-gel　process　catalyzed　by　oxalic　acid　was　used　for　the　preparation　of　SiC　precursor　from　raw　materials　of　tetraethyl　orthosilicate　(TEOS)　and　sucrose.　The　precursor　thus　obtained　was　homogeneous.　Sintered　with　a　certain　heating　program　in　an　argon　flow,　the　precursor　was　converted　into　the　high　surface　area　SiC.　The　high　specific　surface　area　silicon　carbide　was　used　as　catalyst　support　for　ammonia　synthesis.　The　effect　of　the　surface　of　the　support,　promoter　and　the　amount　of　Ru　on　the　catalytic　activity　for　ammonia　synthesis　was　studied.　The　results　show　that　when　the　high　specific　surface　area　SiC　of　113　m2·g_1　is　used　as　support,　the　prepared　SiC-supported　ruthenium　catalyst　has　a　relatively　high　activity　(11.85%)　under　Ru　4wt%,　Ba　4wt%,　K　8wt%,　475°C,　10.0　MPa　and　10　000　h-1.