There is a distinct zone of A-type granite in the western Kunlun Mts. with the scope corresponding to the Kudi mantle steps. The A-type granites generated in Late Indosinian, inter-growthing with Late Hercynian I-type granites. The characteristics of A-type granitic rocks are: enrichment in alkali, LREE, Y, Nb, Zr, lean in Al, Mg, Ca, Ba, Sr, transition elements ,and extended SiO2 contents, which are quite similar to those of A-type granite in Chaelundi, Australia. The research results indicate that the studied granites belong to A2-type which formed in late oro-genic extension environment and intruded in the process of the lithospheric delamination.