Abstract: South and north boundary faults of the Mazha tectonic melange belt have obvious deformation and toughness. Through field regional geological survey, the author aimed to establish a new understanding of the mixed boundary fault zone, and found that the north and south boundary faults have multiple periods of tectonic features of early ductile shear and late brittle activities. The early ductile shear developed a lot of mylonitization and asymmetry rotated porphyroclast phenomenon. Through the petrochemical analysis on north boundary fault arc volcano rock, it is concluded that the widespread magmatite in Mazha tectonic melange belt formed in the island arc tectonic environment on the edge of the plate.