Welding　experiments　of　DP780　high　strength　steel　plate　produced　by　Baosteel　with　IPG　YLR-6000-ST2　fiber　laser　have　been　processed.　The　influence　of　welding　parameters　on　welding　quality　has　been　investigated.　As　well　as　microstructure　and　mechanical　character　of　welding　seam　have　been　analyzed.　The　results　show　that　the　joint　appearance　of　DP780　high　strength　steel　welded　with　IPG　YLR-6000-ST2　fiber　laser　has　good　performance　and　the　mechanics　property　is　good　without　fit-up　gap.　The　microstructure　of　weld　bead　is　columnar　crystals,　mainly　lath-shaped　ferrite,　needle-like　lower　bainite　and　a　small　amount　of　martensite.　Heat-affected　zone　is　narrow　and　the　grain　grows　with　little　size.　The　measured　micro-hardness　values　of　the　sample　decrease　smoothly　from　weld　center　to　base　metal　and　there　does　not　have　softened　zone.