Abstract: Early Paleozoic to Early Mesozoic intrusive rocks are widely distributed in northern Alxa region, Inner Mongolia. The temporal and spatial distribution, magma source components and petrogenesis for these rocks are important for studying the tectonic evolution of northern Alxa, and even for studying the late stage evolution of the southern Central Asian orogenic belt. Mandelinwula pluton, located in the west part of the Yabulai-Nuoergong-Honggueryulin tectonic belt, is mainly composed of granite and monzogranite, and mafic microgranular enclaves (MME). The identified MME has fine-grained textures, sinuous margins and diffuse contacts with the host monzogranites, and various disequilibrium textures and mineral assemblages indicate mingling or mixing processes. LA-ICP-MS zircon U-Pb dating yielded ages of 271±3Ma and 271±2Ma for the monzogranite and MME, respectively, indicating that the Mandelinwula pluton was emplaced in Permian instead of in Early Mesozoic as suggested by previous researchers. Zircon ε_Hf(t) values of the monzogranite and enclaves show a wide range and significant overlap from -18.4 to -10.1 (with T_DM 1.8~2.3Ga) and -23.6 to -9.1 (with T_DM 1.7~2.5Ga), respectively. The source characteristics are similar to those of the intermediate-felsic plutons in the east part of the Yabulai-Nuoergong-Honggueryulin belt of the northern Alxa block. Combined with petrology, geochemistry and Hf-in-zircon isotope studies, the authors propose a plausible magma mixing interpretation for the Mandelinwula monzogranite and MME.