By using of 55931 data of P-S travel time of regional earthquakes in 1981-1996 recorded in the Qinling -Dabie orogenic belt and adjacent areas, seismic tomography on Vp/Vs is carried out and then structures of Poisson’s ratio are deducted. Our major findings are f (1) the σ images in the upper, the middle and the lower crust of the Qinling-Dabie orogenic belt show a pattern of three segments - West Qinling, East Qinling (bounded by Foping-Xian fault) and Dabie (bounded by the Dawn-Luoshan fault), (2) the high a σ in the shallow crust of Qinling are indicative of extensive developed microcracks, (3) the a values in the middle crust of Qinling are lower than those in the upper crust of Qinling, but the a values in the middle crust of Dabie are higher than those in the upper of Dabie - the difference between Qinling and the Dabie may be due to their deferent compositions of rocks, (4) along the Tancheng-Lujiang fault there is a high σ belt in the upper mantle. By using of 55931 data of PS travel time of regional earthquakes in 1981-1996 recorded in the Qinling-Labie orogenic belt and adjacent areas, seismic tomography on Vp / Vs is carried out and then structures of Poisson’s ratio are deducted. Our major findings are f (1) the σ images in the upper, the middle and the lower crust of the Qinling-Dabie orogenic belt show a pattern of three segments - West Qinling, bounded by Foping-Xian fault and Dabie (bounded by the Dawn-Luoshan fault), (2) the high a σ in the shallow crust of Qinling are indicative of extensive developed microcracks, (3) the a value in the middle crust of Qinling are lower than those in the upper crust of Qinling, but the a values ​​in the middle crust of Dabie are higher than those in the upper of Dabie - the difference between Qinling and the Dabie may be due to their deferent compositions of rocks, (4) along the Tancheng-Lujiang fault there is a high σ belt in the upper mantle