Xiaerpu granite is composed of host rock, mafic microgranular enclaves and intermediate-basic dyke swarms, with the development of abundant and typical petrographical evidence of magma mixing. In field outcrops, dark minerals are distributed asymmetrically, and dark mineral aggregates, mafic microgranular enclaves, bands of nonuniform mixing are well developed. Mafic microgranular enclaves show characteristics of strong plastic distortion and clear boundary or transitional relationships with host rocks, with well developed reversed veins and captured feldspar phenocrysts (captured crystals). Basic dyke swarms and mafic microgranular enclaves occur closely and are distributed in the same direction, and basic dyke swarms contain the captured feldspar phenocrysts of the host rock, also traversed by the reversed veins of the host rock. Under the microscope, abnormal zoning of plagioclase and many types of disequilibrium mineral associations are developed in enclaves and bands of nonuniform mixing, with the acicular apatite developed in enclaves. These phenomena suggest that mafic microgranular enclaves and basic dyke swarms might have originated from basic magma formed at the same time as the host rock, and they probably experienced strong magma mixing. Petrographic features provide important evidence for magma mixing of Xiaerpu granite