The　spot　welding　parameters　for　cold-rolled　dual-phase　DP600　steel　in　industrial　trial　production　were　optimized　by　orthogonal　experimental　design　method　with　the　tensile/shear　loads　of　spot　welded　joints　as　the　evaluation　index.　The　welding　window　and　optimal　welding　parameters　were　achieved　by　range　analysis　and　variance　analysis.　The　microstructure　and　tensile/shear　loads　of　the　spot　welded　joints　under　optimized　welding　parameters　were　investigated.　The　results　showed　that　the　welding　current　was　between　9000　A　and　12000　A,　and　the　welding　time　was　between　200　ms　and　500　ms　in　the　welding　window.　The　welding　current　had　most　remarkable　influence　on　the　joint　strength.　With　the　increase　of　welding　current,　the　tensile/shear　loads　increased.　The　maximum　load　14　kN　and　the　maximum　absorbing　energy　45.26　kJ　were　obtained　with　12000　A　welding　current,　200　ms　welding　time　and　2500　N　electrode　pressure.　And　the　microstructure　of　the　resultant　welded　nugget　mainly　consisted　of　lath　martensite.