Abstract：On the basis of regional geological mapping, the authors studied Yanshanian rocks in the Dabie area, re-determined the phases of Yanshanian magmatism and found the existence of a complete orogenic magmatic cycle in the area. They for the first time propose that the late Yanshanian magmatic rocks in the area constitute a bimodal association, which combines with the early Yanshanian magmatic rocks (belonging to high-K calc-alkaline-shoshonitic association) to form a compressional to extensional orogenic magmatic cycle. This is important evidence of Yanshanian orogeny. The features of origin of magmatic rocks have revealed that the lithosphere structure in the area experienced a process from double continental crust to normal continental crust in the Yanshanian stage. The deep geological process was the continuation of underplating and delamination.