Abstract:Longwangzuizi is located in the overlapping position of Qinglong—Jinxi complex structural belt and Xipingpo—Jinxi crust fault, and in the eastern part of the important Qinglong —Jinxi uranium gold polymetallic metallogenic belt in western Liaoning.Based on the petrography, geochemistry and zircon U-Pb dating of the porphyritic biotite granite in Longwangzuizi area, the diagenetic age of the granite is (165.4 ± 1.8) MA , which belongs to the early Yanshanian period.The SiO2 value of the sample is 65.79%~75.61%, the total alkali ALK (Na2O + K2O) value is 7.02%~8.99%, the A/CNK value is 1.49~1.73, the K2O/Na2O value is 0.72~2.34, the AR value is 2.68~4.89, the ritmann index is 1.65~3.04, the consolidation index (SI) is 1.66~9.20, and the magmatic differentiation index (DI) is 78.08~93.17, indicating that the rocks are peraluminous and calc-alkaline I-type granites of high fractionation in the rock series.The total amount of REE in the rocks is high, and the range of variation is large (∑w 93.46ppm~336.97ppm); ∑w (LREE) /∑w (HREE) = 8.07~17, w (LaN /YbN)= 14.53-20.6,the difference between light and heavy rare earths is strong, LREE is enriched and HREE is depleted, REE distribution curve is inclined to the right and nearly straight line "Seagull type", EU is depleted strongly (δEU = 0.01~0.76), which is similar to the geochemical characteristics of uranium bearing granites in South China, indicating that the rocks are beneficial to uranium mineralization.Compared with the original mantle, the rocks have strong losses of Ba, Th, Sr, Zr and Nb, and are obviously enriched with Rb, U and Pb. Based on the geochemical characteristics, diagenesis age and regional structural evolution of rocks, it is considered that the rocks are formed in the post collisional orogenic environment. The intrusion of Yanshanian granite is the main factor of uranium mineralization in the region.