Abstract: In order to understand the action mechanism of yak MSTN, seek for possible method to block its activity and finally realize an efficient growth in yak, MSTN gene was recombinantly expressed in prokaryotic cell and purified for testing its immunogenicity. Firstly, yak MSTN mature peptide gene was cloned using specific primers and reversetranscription PCR method. Secondly, the target fragment was cloned into pET28a(+) vector and then transformed into E. coli BL21 (DE3) for prokaryotic expression. The target peptide was purified from total prokaryotic expression products. Finally, immunogenicity of yak MSTN peptide was detected by ELISA. The MSTN mature peptide gene inserted into the recombinant expression vector contained 330 bp and encoded 109 amino acids in yak. The expression host transformants were induced by adding 0.1 mmol·L-1 IPTG to the LB medium, and the content of target protein was about 21% of the total proteins after six hours of induction. The highly purified yak MSTN mature peptide was obtained by affinity chromatography and its molecular weight was 16.5 ku. The result of ELISA showed that the mature yak MSTN recombinant peptide had an excellent immunogenicity and the titer of rabbit serum antiyak MSTN was 1∶32 000. The study of highly efficient expressed and purified yak mature MSTN peptide with excellent immunogenicity obtained from this study paved a way to study its functional mechanism that may be further explored to improve the meat production performance of yak.