The Qulong porphyry Cu-Mo deposit,generated in the Miocene post-collisional extension environment of the Gangdese Copper(Molybdenum)Metallogenic Belt,is one of the largest porphyry Cu deposits in China.This study reports the noble gas isotopic compositions of vola-tiles released from fluid inclusion reserved in pyrite from the Qulong deposit.3He/4He and 40Ar/36Ar ratios range from 0.54 to 1.015 Ra and 300-359,respectively.Con-centrations of 4He and 40Ar range from 1.77 to 2.62 × 10-8 cm3 STP and 1.7-34 × 10-8 cm3 STP,respectively.The isotopic composition of noble gases indicates that the ore-forming fluids of the Qulong Cu-Mo deposit were a mixture of fluid containing mantle compo-nent,which is exsolved from the porphyry magma,and crustal fluid characterized by atmospheric Ar and crustal radiogenic He.The δ34S values of pyrite and molybdenite range from-0.52‰ to 0.31‰,with an average of-0.12‰,indicating a magmatic origin.More mantle components were involved in the Cu-Mo deposit than in the Mo-Cu deposit in the Qulong-Jiama ore-district.