The southern part of the Zhuguang Mountains is a large granitic composite consisting of Caledonian, Indosinian and Yanshanian granites. This paper reports SHRIMP zircon UPb dating results for four granites located at the joint area of eastern and western sections of the granitic composite. These four granites, namely Changjiang, Qiling, Chikeng and Chashan, yield ages of 160±2 Ma(MSWD = 1.8)、156±2 Ma(MSWD = 2.5)、154±1 Ma(MSWD = 0.41) and 157±3 Ma(MSWD = 2.7)，respectively, which indicates that they are formed during the Early Yanshanian magmatic activity and further verifies that in the Nanling region there was a magmatic activity peak during the period between the Middle and Late Jurassic. The petrological characteristics of these granites and regional geological features support the view that these Early Yanshanian granites were emplaced during the further extension induced by Paleopacific Plate subduction in the vulnerable zone originally generated by the collision between the Indochina Plate and South China Plate in the Indosinian period.