The　diffusion　field　theory　has　been　widely　used　to　interpret　ambient　noise　wave　fields.　Based　on　this　theory,　1-D　subsurface　velocity　structure　inversion　method　is　developed.　However,　few　studies　have　referred　to　the　noise　horizontal　to　vertical　(NHV)　spectral　ratio　inversion　of　3-D　subsurface　velocity　structures,　and　almost　no　effective　3-D　NHV　inversion　tools　have　been　developed.　To　develop　a　useful　tool　for　obtaining　3-D　soil　layer　velocity　structures,　we　combined　the　NHV　forward　calculation　formula　derived　from　diffusion　field　theory　with　the　guided　Monte　Carlo　algorithm　and　then　extended　the　single-point　NHV　inversion　to　multipoint　joint　inversion　through　a　joint　objective　function.　Subsequently,　a　new　3-D　soil　layer　velocity　structure　inversion　method　was　proposed.　Subsequently,　a　synthetic　2-D　case　was　used　to　verify　the　proposed　method.　Finally,　the　proposed　method　was　applied　to　the　Xiangtang　Array　in　Tangshan,　China,　to　identify　the　3-D　velocity　structures　of　the　site　based　on　noise　observations.　The　results　show　that　the　proposed　multipoint　joint　3-D　inversion　method　is　effective　for　identifying　3-D　underground　velocity　structures.