This paper reports LA-ICP-MS zircon U-Pb dating data as well as whole rock major and trace element data from granite pluton in the Yaodonggou area of the North Qilian orogenic belt. The result shows that the pluton was emplaced at 466±2 Ma. The Yaodonggou granite contains high SiO₂ (72.45%~80.18%) and Alk (6.04%~8.12%). Its K₂O content is less than that of Na₂O with K₂O/Na₂O ratio of 0.07~0.71, Ritterman index of 0.96~2.16 (less than 3.3), and A/CNK of 0.94~1.01. The granite belongs to low-medial potassium calcium alkaline series quasi-aluminum rocks. The chondrite-normalized REE patterns show the right-inclined type of LREE enrichment, with a medium negative Eu anomaly and δEu of 0.67~0.81. The primitive mantle-normalized spidergram shows depletion of Nb, Ta, Ti, P and enrichment of Rb, K, U. The P₂O₅-SiO₂ diagram shows the trend of I- type granite. The Y-Rb diagram shows the characteristics of differentiated I-type granite. Combined with the regional geological background, the authors hold that the formation of the Yaodonggou granite was probably related to the northward subduction of the North Qilian Ocean Basin, which led to the back-arc extension and mantle-derived magmatic intrusion and uplift. As a result, the ancient crustal material was remelted to form parent magma, then it was subjected to moderate crystallization differentiation. The magma had the property of island arc magma, which might have been attributed to the fact that the back arc basin was split on the basis of island arc or its magma source area was reformed by subduction plate fluid or melt.