Abstract: In this paper, the chronologic and geochemical researches were carried out on the porphyritic monzonitic granite in Southwest Hongyanjing.The zircon LA-ICP-MS U-Pb dating results show that the zircon U-Pb age of the intrusions is (402.2±4.4)Ma, which indicates that this intrusion was formed in the Early Devonian.Petrochemical and Geochemical data indicate that the porphyritic monzonitic granite are characterized by high Si (68.12%~75.76%)and high alkali (7.69%~9.91%), with A/CNK value of 1.4~1.5.Such geochemical characteristics, such as the rittmann index in sigma(σ)=1.8~3.8 (average 2.38), indicate that this intrusions belongs to the calc-alkaline strong peraluminous series.It displays higher total REE content(ΣREE=175.4~296.76).Trace elements HFSE and Y are well concentrated, but Ba, Sr, Eu, P, and Ti are poorly concentrated.The comprehensive analysis also suggests that the granite is strongly peraluminous S-type granite of the calc-alkaline suite,which was formed in the post-orogenic tectonic environment.