TNNI1 encodes the slow skeletal muscle isoform of troponin I. In the present study, the basic characteristic and expressing profile of the TNNI1 gene was first explored in Gaoyou ducks. Full-length TNNI1 cDNA of Gaoyou duck was obtained using reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The cDNA consisted of a 57-base pair (bp) 50UTR, a 345-bp 30UTR, and a 564-bp open reading frame. The predicted protein was predicted to be hydrophilic, nonsecretory protein and contained 17 phosphorylation sites. Multiple alignments and phylogenetic tree analyses showed that the predicted protein was relatively conserved in avian. TNNI1 mRNA could be detected in every tissue analyzed at 70 days of age, and the muscle tissues had relatively high expression level, with the highest level seen in leg muscle. The TNNI1 gene was differentially expressed in the breast muscle and leg muscle during embryonic and posthatching development. Our findings reveal the sequence characterization and expression patterns of the TNNI1 gene, which may provide correlative evidence that TNNI1 gene plays an important role in duck muscle fiber development and meat quality.