In　order　to　effectively　detect　creep　cracks　generated　inside　the　high-temperature　hydrogen　furnace　tube,　a　set　of　in-service　high　temperature　hydrogen　furnace　tube　creep　crack　detection　system　was　developed　based　on　the　ultrasonic　transmission　detection　method,　using　the　directional　transmitted　wave.　Considering　the　detection　efficiency,　a　multi-channel　detection　sensor　ring　was　designed,　a　sweeping　method　was　proposed　and　an　integral　detection　system　was　developed.　A　crawling　mechanism　was　designed　to　achieve　the　automatic　scanning　of　the　furnace　tube.　Finally,　the　developed　system　was　applied　in　the　experimental　examination,　in　which　it　can　effectively　characterize　the　pre-set　defects　by　its　location　and　quantification.　©　2022　IET　Conference　Proceedings.　All　rights　reserved.