The Dabie Orogenic Belt,which involves the deep subduction and continental crust collision in the Triassic,is one of the major continental collision zones on the globe. The Yangtze Block subducted to mantle depths of ca. 200km beneath the North China Block,which resulted in the formation of UHP metamorphic terranes. In addition,the area underwent extensional tectonic collapse and post-orogenic magmatism/volcanism in the early Cretaceous. Here,we collected abundant local earthquakes and performed a double-difference tomographic study to construct the crustal velocity structure in the Dabie Orogenic Belt(29°~34°N,114°~119°E)and study the relationship between crustal structure and post-orogenic magmatism/volcanism. Results show there is a low-velocity structure(Lv1)beneath the Dabie Orogenic Belt,which might be melting material of mantle source which might be associated with magmatism and/or volcanism in the early Cretaceous. The upwelling asthenosphere can be generated by the break-off of the subduction slab or low crustal/lithospheric delamination in the Mesozoic in the Dabie Orogenic Belt. The upwelling asthenosphere might invade into the crust and form the melting material. Finally,magmatism and volcanism were likely to be triggered by the melting material in the crust. Meanwhile,there is another large-scale low-velocity structure(Lv2)located at the Hefei Basin,which might be generated by the sedimentary layer in the shallow. There is a dipping vestige of high velocity beneath the Dabie Orogenic Belt,which might be the Xiangfan-Guangji fault or northward subduction relic.