Dioritic enclaves are widely distributed in Badashi biotite-monzogranite of the East Tianshan Mountains. These dioritic enclaves and their host granite are different in mineral association, but species of the same mineral within them are similar to each other. In comparison with the host granite, the dioritic enclaves are higher in Fe, Mg, Ti, Ca and richer in HREE, Sr, but lower in Na, K, Si and poorer in Ba, Th, Hf, Zr. Zircon LA-ICP-MS U-Pb dating gave ages of 301±1 Ma and 298±2 Ma for the dioritic enclaves and their host granite, respectively, indicating their Early Permian emplacement. The dioritic enclaves and their host granite have positive in εNd(t)（＋4.15 and ＋3.06）values and relatively low (87Sr/86S r)i（0.70412 and 0.70475） with fairly similar model ages tDM（812 M and 944 Ma, respectively). It is suggested that the dioritic enclaves and their host granite were derived from the same parental magma that resulted from partial melting of the Neoprot-erozoic depleted-mantle-sourced juvenile crust. Petrologic, geochemical and isotopic studies prove that the Badashi dioritic enclaves are autoliths and the earlier products generated by crystal fractionation of the host granite parental magma