Objective To prepare and identify a polyclonal antibody against rat myostatin and investigate myostatin expression in the rat atrophic gastrocnemius muscle after tibial nerve crush. Methods The purified fusion protein was used as antigen to immunize rabbits for the preparation of polyclonal antibody. The polyclonal antibody of the protein was measured by enzyme linked immunosorbent assay (ELISA), western-blot and immunochemistry. Myostatin protein expression levels in normal and atrophic gastrocnemius muscle were detected by western-blot and immunochemistry assays. Results The GST-myostatin had a purity of 96% and possessed high titer and specificity. The level of myostatin in gastrocnemius muscle significantly increased one week after tibial nerve crush, reached the peak on day 14, and then returned to normal level on day 28. Conclusion We have successfully made antiserum of rat myostatin and found that the expression level of myostatin protein in the gastrocnemius after tibial nerve crush-induced atrophy was time-dependent. This study provides an experimental basis to clarify the possible role of myostatin during skeletal muscle atrophy.