The Xinping granite-porphyry occurring in the Xinping gold mining area is located in the middle part of the Dayaoshan Au metallogenic belt, eastern Guangxi. The results suggest that the Au-Mo-polymetallic mineralization is closely related to the granitic igneous activity. Zircons of the granitic porphyry are analyzed using LA-ICP-MS U-Pb isotopic method, which gives a weighted mean 206Pb/238U age of (462.9 ± 6.4) Ma. It reveals a mid-Ordovician magmatic timing, providing a lower constraint for the mineralization age.