Objectives: The Xiangshan uranium deposit is the largest volcanic type uranium deposit found in China so far. The Xiangshan volcanic—intrusive complex is composed of rhyodacitic lava, porphyroclastic lava and granitic porphyry. The Xiangshan volcanic—intrusive complex has been previously studied in detail on its petrography, mineralogy, lithochemistry and geochronology. In recent years, with progress in deep drilling in the western Xiangshan area, appearance of porphyroclastic lava — rhyodacite —porphyroclastic lava downward in drilling cores has been found. Previous geochronological study results could not explain this phenomenon. Methods：In this study, we collected samples from the upper and lower layers of porphyroclastic lavas and the rhyodacite in between in the western part of the Xiangshan complex, and from three granitic porphyry dikes in the western and northern Xiangshan area. U- Pb age and Hf isotope of zircon havebeen conducted on these samples by LA- ICP- MS and LA- MC- ICP- MS analysis, respectively. Results：The zircon dating results show that age of the rhyodacite is 139.7±1.0Ma, ages of the upper and lower layer of porphyroclastic lava are 135.3±0.9Ma and 129.9±0.9Ma, respectively. The three granite porphyry dikes from different locations have various ages of 125.4±1.0Ma, 134.4±1.3Ma, 148.8±2.3Ma, respectively. The results zircon Hfisotope compositions of this study show that various rocks of the Xiangshan volcanic—intrusive complex have similar zircon εHf(t)values ranging from -4.9 to -10.6, and Hfisotope two stage model ages between 1478 and 1844Ma. Conclusions：It can be concluded that the Xiangshan volcanic—intrusive complex may have been formed by magmas originated from partial melting mainly of basement para- metamorphic rocks that was derived from the crust differentiated from the mantle in the Mesoproterozoic era.Combined with the photomicrograph of both the upper and lower porphyroclastic lavas, we propose a formation model in that the lower porphyroclastic lava was formed later than the upper porphyroclastic lava,and the lower porphyroclastic lava was actually a kind of ultra- shallow intrusive rock intruding along with the tuff below the rhyodacite. These results show that the magmatism in the Xiangshan was active for a long period (about 24Ma) rather than a short and concentrative magmatic activity thought by previous researchers, which was an important factor favorable for uranium mineralization.