MS1470　steel　is　mainly　used　in　the　automotive　industry,　which　has　high　strength,　light　weight　and　low　cost.　However,　there　always　appear　grains　coarsening,　brittle　increasing,　lower　intensity　and　other　issues.　To　solve　this　problem,　we　have　analyzed　the　welding　process,　the　fracture　morphology　and　microstructure　etc.　The　results　shown　that　the　microstructure　were　mainly　ferrites　and　lath　martensites.　However,　grains　coarsening　in　the　HAZ　were　serious,　and　fracture　failure　also　occurred　in　the　heat　affected　zone.　Meanwhile,　MS1470　steel　had　formed　a　small　amount　of　pores　during　rolling　process,　which　also　is　an　important　reason　for　cracks　formation.