The Gaocheng deposit is a newlydiscovered largesized silverleadzinc polymetallic deposit in the Yunkai area of western Guangdong. Orebodies occur mainly in structural fractures of biotite granitic rock and show close spatial relation to biotite granitic rock. This phenomenon is significantly different from majority of China’s hydrothermal vein leadzinc deposits in that the latter has orebodis occur mainly in strata or contact zone between rockbodies and strata. The timing and genetic relationship between granite and ore deposits is unclear at present. This study carried out highprecision SHRIMP UPb zircon analyses for the zircons from granitic mylonite, biotite granite and tonalite in the Gaocheng deposit. Three zircon 206U/238Pb concordant ages of 451.5±2.8 Ma (MSWD=0.27, n=7), 463.3±3.3 Ma (MSWD=1.4, n=10) and 450.0±4.5 Ma (MSWD=3. 4, n=12) were obtained for granitic mylonite, biotite granite and tonalite, respectively, revealing that the rocks crystallized at 450~463 Ma (Middlelate Ordovician) and should be the products of the Caledonian magmatism and also carry some MesoNeoproterozic basement information. These ages are 20~30 Ma earlier than the crystallization age of biotite granites (429 Ma and 438 Ma, early Silurian). Biotite granitic rock, as the orebearing country rocks, formed earlier than oreforming period of the Gaocheng polymatallic deposit, indicating that the deposit formed likely after Late Cretaceous. Based on the regional geological data and the latest research results, it can be concluded that one thermal tectonic magmatic event occurred in the Gaocheng mining area at Caledonian period (450~463 Ma), which was the product of partial melting of the MesoNeoproterozoic crustal material caused by Early Paleozoic intracontinental WuyiYunkai orogeny in the background of intracontinental subduction.