Aiming　at　the　problem　of　quality　evaluation　for　resistance　spot　welding　of　hot　stamping　high　strength　steel,　the　dynamic　resistance　information　of　the　normal　welding　spot,　the　welding　spot　with　incomplete　fusion,　and　splash　welding　spots　extracted　by　the　LabVIEW　system　were　analyzed.　A　five-digit　generalization　method　was　proposed　to　set　the　threshold　value.　Results　show　that　the　dynamic　resistance　curves　of　the　welding　spot　with　incomplete　fusion　and　the　normal　welding　spot　have　obvious　differences　in　the　characteristic　parameters　such　as　the　parameters　of　speed,　falling　range,　ending　value　and　effective　value.　When　the　splash　welding　spot　happens,　the　dynamic　resistance　curve　will　drop　sharply.　The　least　squares　fitting　is　performed　on　the　dynamic　resistance　curve　of　the　splash　welding　spot　and　the　actual　dynamic　resistance　curve　and　the　fitting　dynamic　resistance　curve　is　subtracted　to　calculate　the　root　mean　square　values,　namely,　splash　characteristic　index.　Therefore,　on　the　basis　of　characteristic　indexes,　on-line　evaluation　of　the　welding　quality　is　obtained　and　good　results　are　achieved.　©　2018,　Editorial　Department　of　Journal　of　Beijing　University　of　Technology.　All　right　reserved.