The Duolong deposit is located on the western edge of the Qiangtang terrane to the northwest of the The Bangong- Nujiang suture zone in Tibet. Based on detailed geochemical research, this paper discusses the genesis and tectonic setting of siliceous rocks in the Duolong deposit. These siliceous rocks share SiO2 content of 92.83%~93.97%, Si/Al ratios of 48.98~49.56, MnO/TiO2 ratios of 0.36~0.64, Al2O3/(Al2O3+Fe2O3) ratios range from 0.77 to 0.81, suggesting that these rocks form at the continent margin and contain a relatively high proportion of terrigenous muddy sediments. They share total REE content ranging from 30.83×10-6 to 34.59×10-6 and LREE/HREE ratios ranging from 6.71 to 6.93. Both the chondrite- normalized and the North American shale- normalized REE patterns show that siliceous rocks are enriched with LREE, and have slightly positive Ce anomaly and negative Eu anomaly. Besides, their trace elements are badly depleted, except the chalocophile elements (Such as Cu and Pb). These siliceous rocks share V content of 7.83×10-6~ 8.84×10-6 and V/Y ratios of 1.25~1.48. Moreover, these rocks have δ30 SiNBS-28‰ values (1.0‰~1.1‰) and δ18OV-SMOW‰ values of 20.3‰~20.8‰, respectively. Comprehensive analysis shows that the Duolong siliceous rocks formed between the late Jurassic and the Early Cretaceous in a continental margin environment and belong to biogenic siliceous rocks.The southern Qiangtang terrane was in a continental margin arc environment between the late Jurassic and Early Cretaceous. The Bangongco- Nujiang oceanic lithosphere was still undergoing northward subduction beneath the southern Qiangtang terrane and the oceanic basin have not closed completely at that time.