Abstract: 8 pieces of ore samples from 2 304^# and 2 312^# drillings in Duobuza copper deposit of Tibet were selected to test their Pb isotopic composition. The test analysis showed that with the drilling depth increasing，Pb isotope ratios in the strata and porphyry are constantly improving on the whole，and Pb isotopic ratio in the ore-bearing strata is higher than that in ore-bearing porphyries. Lead comes mainly from the subduction zone of the crust and the mantle and partly from the orogenic belt. And its tectonic background is in the arc environment.

Key words: Pb isotopes, Duobuza copper deposit, Duolong ore concentration area, Tibet