This　article　introduces　the　property　of　magnetic　field　distribution　and　application　of　TMS　developed　by　BJUT.　The　TMS　generates　time-varying　magnetic　field　to　stimulate　the　particular　area　in　human　brain.　To　obtain　the　distribution　of　magnetic　density,　we　carried　out　survey　by　utilizing　a　Gauss　meter,　from　three　aspects:　the　distribution　of　magnetic　density　in　axial　direction,　in　radial　direction　and　around　the　circle　which　hold　the　maximal　magnetic　density.　Moreover,　further　experiment　on　heroin　addicts　is　developed　as　an　application　of　TMS.　As　a　result　of　a　course　of　treatment,　the　amplitude　and　latency　of　N270　generated　by　heroin　addicts　were　decreased　or　shortened,　and　the　brain　function　of　heroin　addicts　changed　as　well.　TMS,　consequently,　has　effective　therapy　on　heroin　addicts.