A　dynamic　induction　heating　method　was　used　to　inhibit　the　formation　of　martensite　in　heat-affected　zone　(HAZ)　of　U71Mn　steel　rail　after　surface　welding.　The　inhibition　of　martensite　structure　was　characterized　by　optical　microstructure　analysis　and　microhardness　testing.　The　experimental　results　showed　that　when　the　U71Mn　steel　rail　was　welded　in　cold　welding　condition,　cracks　would　form　directly　in　the　heat-affected　zone,　and　the　microstructure　was　martensite.　With　the　increase　of　preheating　and　post-heating　temperature,　the　amount　of　martensite　reduced　significantly.　When　the　preheating　temperature　was　320　and　post-heating　temperature　was　550　,　the　martensite　structure　could　be　inhibited　completely,　and　the　heat-affected　zone　consisted　of　sorbite　structure　whose　size　was　smaller　than　pearlite　structure　in　the　base　metal.　The　microhardness　of　the　heat-affected　zone　also　distributed　uniformly.　©,　2014,　Harbin　Research　Institute　of　Welding.　All　right　reserved.