The　Co-Al　coating　was　deposited　on　Ni-based　superalloy　DZ125　by　pack　cementation.　The　lifetime　and　interdiffusion　behavior　of　the　Co-Al　coating　on　the　Ni-based　superalloy　at　1050　degrees　C,　1075　degrees　C　and　1100　degrees　C　were　investigated.　Surface　oxidation　and　interdiffusion　between　the　coating　and　the　substrate　led　to　depletion　of　Al　in　the　coating,　and　beta-Ni(Co)Al　was　gradually　degraded　into　gamma　and　gamma＇　phases.　Oxidation　activation　energy　of　the　coating　was　calculated　through　oxidation　weight　gain　curves　of　different　temperatures.　The　formula　of　the　coating　lifetime　related　to　the　coating　thickness　and　the　temperature　was　established　by　calculating　intermediate　parameters.　The　lifetime　determined　by　the　formula　and　experiment　showed　good　agreement.　(C)　2019　Elsevier　B.V.　All　rights　reserved.