Ammonia　is　an　important　chemical　for　synthesized　fertilizers　traditionallyand　for　a　potential　energy　vector　increasingly.　Industrial　ammonia　synthesis　through　theHaber-Bosch　process　is　energy-intensive　and　requires　advanced　materials　to　catalyzeammonia　synthesis　under　mild　conditions,　whereas　the　utilization　of　ammonia　as　ahydrogen　carrier　via　ammonia　decomposition　is　facing　a　similar　situation　as　well.　Thedeveloped　second-generation　Ru-based　catalysts　performs　superior　activities　overcommercial　Fe-　or　Ni-based　catalysts;　however,　it　remains　challenging　to　constructeffective　Ru　catalysts　to　achieve　the　usage　of　Ru　metal　affordably　as　well　as　furtherunderstanding　the　nature　of　Ru　catalysis.　This　Perspective　summarizes　the　recentcontributions　in　engineering　Ru-based　catalysts　via　various　strategies　and　related　catalysisin　ammonia　synthesis　and　decomposition,　and　it　discusses　the　similarities　and　differencesof　Ru　catalysis　in　these　reactions.　Finally,　an　overview　of　this　area　and　opportunities　forfurther　investigation　are　also　provided.