Ruthenium　catalysts　are　considered　as　the　second-generation　catalysts　for　ammonia　synthesis　following　iron　catalysts.　The　article　summarizes　advances　in　research　and　industrial　application　of　ruthenium-based　ammonia　synthesis　catalysts.　Ruthenium　catalysts　are　known　to　be　quite　sensitive　to　the　nature　of　supports,　promoters　and　precursors　in　ammonia　synthesis.　The　different　characteristics　and　kinetics　between　ruthenium　catalyst　and　iron　catalyst　are　described.　Kellogg　advanced　ammonia　process　(KAAP)　supplies　the　strong　support　for　industrial　application　of　ruthenium　catalysts.