Granodiorite porphyrite and granite porphyry are respectively exposed in Yilanbasitao and Wulangdaban of western Nilka County, Xinjiang. According to their petrological and geochemical characteristics as well as regional geological evidence, the authors have reached the conclusion that the two granite bodies are products of magmatic invasion at the continental extension stage after the closure of Tianshan Paleozoic oceanic basin, and that they were formed by partial melting of the lower crust.