In　previous　work,　considering　the　complementarities　of　the　classic　magnetic　flux　leakage　(MFL)　and　elasto-magnetic　(EM)　techniques,　we　proposed　a　novel　sensor　to　measure　the　biased　pulse　magnetic　response　in　steel　stay　cable　for　the　detection　of　surface　and　internal　flaws.　In　this　study,　a　crawler　robot　is　developed　to　carry　the　novel　sensor　for　large-diameter　steel　stay　cable　inspection.　The　entire　robot　system　consists　of　a　drive　mechanism,　pre-loading　mechanism,　power　supply　and　motor　control　module.　The　load　capacity　and　the　maximum　climbing　speed　of　the　robot　are　experimentally　evaluated.　Finally,　the　proposed　crawler　robot　equipped　with　MFL　devices　is　applied　for　inspecting　defective　steel　stay　cable　in　laboratory.　The　testing　results　show　that　the　crawler　robot-based　system　can　successfully　detect　both　surface　and　internal　defects　in　large-diameter　steel　stay　cable.　©　APWSHM　2018.　All　rights　reserved.