Abstract: In order to gain the duck FST exogenous protein and to elucidate about its role in muscle development and reproduction, the total RNA was extracted from adult female duck and the FST coding domain sequence was cloned using RT-PCR method. The duck FST mature peptide cDNA was inserted into pET-32a (+) vector, and transformed into Escherichia coli Rosetta, and then it was induced by IPTG, after that, the recombinant expression products were detected by SDS-PAGE and confirmed by Western blotting analysis. The results of sequence analysis showed that the full duck FST coding domain sequence was 1 032 bp, encoding 343 AA, and the deduced CDS amino acid sequence contains a 28 AA putative signal peptide. The FST amino acid sequence of duck was composed of four domains, including the N-domain, Domain Ⅰ, Domain Ⅱ and Domain Ⅲ. The follistatin Domain Ⅰ in FST was conservative between the duck and mouse, whereas there were many variations between DomainⅡand Domain Ⅲ. The results of SDS-PAGE showed that the molecule weight of induced protein was about 52 ku and display a positive reaction by Western blotting analysis. These results indicated that the three follistatin domains in duck have different roles, and it can be concluded that Domain Ⅰ is mainly related to muscle development, and the Domain Ⅱ and Domain Ⅲ are important for the animal reproduction. The duck FST protein has been gained successfully and these results will be benefit for further researching the effects of FST on promoting muscle growth and egg production of duck in the future.