Abstract: Analyses of large amount of volcanic rock samples on the northern edge of Dabie Mountain show that the geo-chemical behaviors of the main elements of the volcanic rocks in the study area are alkali-calcic, while that of the rare earth elements are of enrichment of light rare earth elements. The relationships between the compositions of volcanic rocks and the tectonic settings are further studied. It is believed that the volcanic rocks would have been formed in a tectonic setting related with the decoupling of the root of the orogenic zone after plate subduction and collision.