We have measured 3He/4He of natural gases in 5 sedimentary basins in Xinjiang, NW China. As much as approximately 7% of the helium in the Xinjiang basins is mantle-derived. Mantle-derived helium in foreland sub-basins reflects the injection of mantle fluids beneath the orogenic mountains through thrust faults. Purely radiogenic helium occurs extensively in the center of individual sedimentary basins. The possible mantle-derived CO2 in Tarim basin is proposed.