Objective The mechanism of the fibrosis in muscles with progressive muscular dystrophy is not clear. Transforming growth factor β 1 (TGF-β 1), which can induce the extracellular matrix aggrogation, has roles in fibrogenesis and tissue repair. This study aims to explore the possible correlation between the immunolocalization of TGF-β 1 in muscle and fibrosis, and to study the mechanism of muscle progressive damages in children with progressive muscular dystrophy. Methods Eighteen children with progressive muscular dystrophy, including 7 casese of Duchenne muscular dystrophy (DMD), 6 Fukuyama type and 3 non-Fukuyama type congenital muscular dystrophy (FCMD and nFCMD), 2 Becker muscular dystrophy (BMD), were involved in this study. Thirteen cases of non-muscular disease served as the controls. The level of TGF-β 1 expression from biopsied frozen muscle were assayed by the immunohistochemical method and Western blot analysis. Results TGF-β 1 of active and latent forms were strongly expressed in the muscle fibers and emdomysium of the muscle in CMD and DMD, and the levels of expression in CMD were significantly higher. The Western bloting results also showed a stronger TGF-β 1 expression in FCMD than in DMD. TGF-β 1 expression levels in both FCMD and DMD were significantly higher than in controls. Conclusions The fibrosis in muscles might be one of the important causes of progressive muscular lesions in children with progressive muscular dystrophy.