Three-dimensional　magnetic　dipole　model　is　formulated　for　the　stay　cable　with　95　mm　diameter.　The　magnetic　flux　leakage　field　induced　by　the　broken-wire　flaw　in　the　3D　space　is　analyzed.　The　spatial　distribution　of　the　axial　component　of　the　leakage　field　is　highlighted　and　discussed.　Scanning　system　is　constructed　to　measure　the　axial　component　of　the　leakage　field.　Experimental　results　verify　the　accuracy　of　the　magnetic　dipole　model　on　leakage　field　detection.　Threshold　method　is　applied　to　estimate　the　effective　diffusion　angle　of　the　axial　component　of　the　leakage　field　along　circumferential　direction　as　±6°,　which　determines　that　the　minimum　number　of　elements　in　the　sensor　array　is　30.　A　circular　magnetic　flux　leakage　sensor　array　is　developed　for　the　stay　cable.　With　the　lift-off　of　8　mm,　the　sensor　array　can　successfully　detect　multiple　surface　broken-wire　flaws　by　providing　a　scanning　image　to　the　cable.　The　effectiveness　of　the　element　number　in　the　array　on　the　quality　of　the　scanning　image　is　discussed.　This　study　provides　a　reference　for　designing　circular　magnetic　flux　leakage　sensor　array　for　surface　flaws　detection　in　large-diameter　stay　cable.　©　2019,　Science　Press.　All　right　reserved.