Abstract: Located in the north of the JinshajiangHonghe porphyry copper metallogenic belt, the Yulong deposit is a giant porphyry copper-molybdenum deposit. This study provides the highprecision Re-Os dating of the mineralization age. The Re-Os model ages for 5 molybdenite samples are from 39.29 Ma to 41.29 Ma. According to the best-fit calculation for 5 samples, the Yulong deposit yield an isochron age of (41.6±1.4) Ma. These data indicate that the mineralization occurred in a very short period with mineralization age span of about 1.5 Ma. And it also implies the special metallogenic environment and metallogenic mechanism of the Yulong porphyry copper-molybdenum deposit.