Abstract: OBJECTIVE To explore the mechanisms that Huangqi injection improve the muscle atrophy induced by sciatic nerve injection injury in rats. METHODS Twenty four SD rats, either ♀ or ♂, were randomly divided into four groups named the normal group, the model group, the negative control group, and the Huangqi injection group. Muscle weights were weighed by scales, the cross-sectional area of muscle fibers were measured under Leica image analyzer after HE staining, the collagen fibers in musculi peronaeus longus were observed by VG staining. RESULTS After sciatic nerve penicillin injection 2 weeks, compared with the normal group, the model group rats walked with a limp, musculi peronaeus longus shrank and lightened, muscle color darkened, cross-sectional area of muscle fibers decreased, proliferation of collagen fibers was obvious. However, the above changes were far worse in the negative control group and significantly improved in the Huangqi injection group. CONCLUSION Huangqi injection can improve sciatic nerve penicillin injection-induced muscle atrophy by decreasing the hyperplasia of collagen fiber in peroneus longus muscle in SD rats.