The source of granitic magma was complex in the postcollision stage and needs to be further studied by using various isotope methods. The Alamas granitoids is distributed in the eastern section of the West Kunlun orogenic belt and of important significance for understanding the continental growth evolution after the closure of the ProtoTethys. Previous studies have shown that the Alamas granitoids was the product of partial melting of an ancient, deep crustal source in the postcollision stage. In order to understand the source characteristic of the Alamas granitoids, PbHf isotopic compositions of the granitoids were analyzed. The results show that the εHf (t) values range from -95 to -32 (averaging -56) and the two stage Hf model ages range from 1633Ma to 2028 Ma, indicating that the Alamas pluton likely sourced from the partial melting of an ancient, deep crust. The granitoids have 206Pb/204Pb values between 18382 and 19333 (averaging 18784)，207Pb/204Pb values between 15589 and 15642 (averaging 15614), 208Pb/204Pb values between 38585 and 39080 (averaging 38800), μ values from 945 to 948 (averaging 946), and ω values from 3380 to 3814 (averaging 3616). In the discrimination diagram, these samples are plotted mostly in the field of the upper crust rocks, indicating that the source area of the Alamas pluton is characteristic of high Pb isotope. Therefore, addition of a minor amount of high Pb isotopic material (sediments) into magmatic source resulted in diversity of material source for formation o f the Alamas pluton in the postcollision stage.