Objectives:Danjin area, Zhenglan Banner, Inner Mongolia is located in the southern part of Great Hinggan magmatic activity belt. Some uranium prospecting achievements have been made in this area in recent years, but the age and background of uranium mineralization are not clear. Based on the study of the host volcanic rocks and uranium mineralization age in Danjin area, this paper discusses the diagenetic mineralization age and metallogenic background.Methods:8 geochemical samples and 2 rock zircon U-Pb age samples were taken in DanJin region, and 11 uranium ore samples were taken from the deep ore body of the borehole.Zircon isotopic datingwas completed in the laboratory of Beijing Yandu Zhongshi Testing Technology Co., Ltd. This test was completed by LA-Q-ICP-MS analysis. The laser ablation system is New Wave UP213, and ICP-MS is Brooke M90. In U-Pb isotopic dating, zircon standard GJ-1 was used as external standard for isotopic fractionation correction. GJ-1 was analyzed twice for every 5~10 sample points. The content of Microelements in zircon was quantitatively calculated by using SRM610 as external standard and Si as internal standard. According to the micrograph of zircon, the zircon dating area is selected, and the denudation spot diameter is 30 μm.Theisochron age analysis of U-Pb in uranium ore was completed in Analtical Laboratory of BRIUG. After crushing and gravity separation, the sample powder with high purity was selected for experimental test. IsoprobeT hot surface ionization mass spectrometer was used in the experiment.The determination of major elements, trace elements and rare earth elements in chemical analysis samples was completed in the laboratory of ALS Chemex(Guangzhou) Co Ltd. After the sample is crushed, 300 g is separated and ground to 75 μ m (200 mesh). The content of rare earth trace elements is determined by ME-MS81 fusion inductively coupled plasma mass spectrometry, and the main elements of rocks are precisely analyzed by ME-XRF26X fluorescence spectrometer fusion method.Results:Based on the study of the field characteristics, microscopic characteristics, geochronology and geochemical characteristics of the host volcanic rocks in Danjin region, as well as the uranium metallogenic age, the rock types of the volcanic rocks are identified in detail, the diagenesis and metallogenic age are determined, and the petrogenesis. The zircons collected from the host volcanic rocks have a zonal structure with Th/U values greater than 0. 1, which is consistent with the magmatic zircons. LA-ICP-MS zircon U-Pb isotopic dating shows that the volcanic rocks were formed in the early Cretaceous (143. 8 ± 0. 5 Ma and 141. 5 ± 0. 5 Ma). After U-Pb isotopic dating of uranium ore, the metallogenic ages are respectively the late Early Cretaceous (113. 0 ± 1. 0 Ma) and the late Cretaceous (80. 6 ± 2. 6 Ma). All samples of volcanic rocks are rich in SiO2(78. 65% ~ 80. 26%); K2O (4. 10% ~ 6. 58%), K2O / Na2O value is greater than 2. 34, europium negative anomaly (δ EU = 0. 05 ~ 0. 10). They are enriched in LREEs relative to HREEs. All the samples are relatively enriched in LILEs (e.g., K and Rb) and depleted in HFSEs (e.g., Nb, Ta, P and Ti).Conclusions:The host volcanic rocks in Danjin region were formed in the early Early Cretaceous, belonging to A-type rhyolite. The magma originated from the partial melting of continental crust. The uranium deposits were formed in the late Early Cretaceous and late Cretaceous, which denied that the previous uranium mineralization occurred in the process of rhyolite porphyry emplacement in the late stage of the volcanic activity, and believed that the uranium mineralization may be related to the late Early Cretaceous and late Cretaceous volcanism. The area with deep source structure superimposed near the deep rhyolite porphyry is an important prospecting area.