The　multi-pulse　laser　treatment　of　port-wine　stains　(PWS)　has　gained　much　attention　owing　to　its　considerable　effect　on　deep　and　large　PWS　vessels　and　the　less　damage　to　the　epidermis.　To　reveal　the　mechanism　of　the　thermal　damage　to　the　vessels　caused　by　the　multi-pulse　Nd:YAG　laser,　an　integrated　numerical　model　of　the　multi-pulse　laser　treatment　of　PWS　was　developed　by　combining　the　voxelbased　Monte　Carlo　(VMC)　method　for　light　propagation　calculation,　the　particle　form　of　Pennes　bioheat　transfer　model　for　heat　transfer　calculation,　and　the　non-Newtonian　moving　particle　semi-implicit　(MPS)　method　for　blood　flow　and　coagulation.　An　in　vitro　experimental　platform　was　constructed　to　visualize　coagulation　caused　by　multi-pulse　Nd:YAG　laser　irradiation　of　the　blood　in　a　capillary　tube.　Numerical　results　of　coagulation　shape　and　area　agreed　well　with　experimental　results,　confirming　the　validity　of　the　proposed　model.　Using　this　integrated　model,　the　thermal　damage　mechanism　of　the　multi-pulse　Nd:YAG　laser　treatment　of　PWS　was　revealed:　When　a　blood　vessel　is　completely　obstructed　by　coagulation,　the　blood　flow　is　stopped,　and　subsequent　laser　pulses　always　irradiate　the　same　coagulated　area　and　the　absorption　of　laser　energy　is　increased;　as　a　result,　the　thermal　effects　of　subsequent　laser　pulses　improve　remarkably.　Finally,　the　applicable　range　of　the　multi-pulse　Nd:YAG　laser　and　optimal　laser　parameters,　including　frequency,　fluence,　and　pulse　number,　for　clinical　practice　are　recommended.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.