The　diffuse　field　theory　can　comprehensively　consider　the　contributions　of　various　types　of　wave　fields　in　ambient　noise.　The　noise　horizontal-to-vertical　spectral　ratio　(NHV)　based　on　diffuse　field　theory　links　surface　observation　with　an　intrinsic　property　of　the　underground　medium.　Naturally,　it　allows　for　the　inversion　of　the　velocity　structure　of　soil　layers.　There　is　an　urgent　need　to　develop　fast　and　effective　NHV　inversion　tools　to　estimate　velocity　structure　for　soil　layers.　Combining　the　genetic-simulated　annealing　algorithm　and　forward　calculation　of　NHV　based　on　diffuse　field　theory,　we　proposed　a　global　inversion　method　to　determine　the　velocity　structure　of　soil　layers.　The　sensitivity　analysis　of　the　model　parameters　shows　that　the　Vp,　Vs　and　h　of　the　soil　layer　and　the　Vs　of　the　rock　layer　are　the　main　affecting　factors　of　NHV,　the　influence　of　the　density　of　soil　and　rock　layers　on　NHV　can　be　ignored.　Through　the　verification　of　synthetic　cases,　the　observation　of　the　Xiangtang　vertical　array,　and　comparison　with　a　similar　method,　we　have　proved　that　good　inversion　results　can　be　obtained　using　our　proposed　method.　This　proposed　method　can　offer　an　efficient　and　low-cost　way　to　estimate　site　velocity　structures.