Both granites of Tongcun and Dexing district are highK calcalkaline, magnesian Itype granites. Texture of Tongcun granodiorite is porphyaceous while Dexing granodiorite porphyry is porphyritic. Granites in Tingcun district is characterized to be rich in Si and K, the ratio of A/CNK and K/(K+Na) is less than rocks in Dexing district. The features of trace elements, isotopes and petrolography of Tongcun and Dexing granites suggest that the origin of the first be mainly crust while the latter be crustmantle thrived and the reason might be connected with their distinct tectonic settings. It is concluded that Tingcun and Dexing porphyries were emplaced in a continental arc setting coupled with westward subduction of the palaeopacific plate. Partial melting involved the subducted slab, with generated melts interacting with the lithospheric mantle wedge during medium to late Jurassic. The fo2, evolution degree and contamination degree of Tongcun orebearing porphyry is higher than Dexing porphyry. Further study of the reason of distinct scale in coetaneous deposits in such a short distance is worthy studying.