Abstract: In order to explore the biological characteristics of SCAI coding protein and its mRNA expression level in Cervus canadensis antler tissues, the full-length CDS sequence of Cervus canadensis SCAI was cloned by PCR,the similarity alignment and phylogenetic tree construction were carried out after sequencing. The composition, structure and physicochemical properties SCAI protein were analyzed by bioinformatics method. The expression level of SCAI mRNA in antler tissue were detected by Real-time quantitative PCR. The results showed that the full length of the SCAI gene CDS region in Cervus canadensis was 1 821 bp, which had high similarity and close genetic relationship with white-tailed deer, and had low similarity and far genetic relationship with chicken. SCAI encoded 606 amino acids, and the relative molecular weight was 70 337.48. The theoretical isoelectric point was 8.85 and the average hydrophilic coefficien was-0.433, indicating that SCAI protein was a hydrophilic protein. There were 57 potential phosphorylation sites in SCAI proteins but no signal peptides. Subcells were mainly localized in the nucleus, so it was not secretory proteins. The structure of α helical and irregular coil was the most in the secondary structure, so SCAI was unstable protein. The expression levels of SCAI gene in skin of red deer antler was the highest, followed by cartilage, which was the lowest expression in mesenchyme and precartilage. These results indicated SCAI gene plays an important role in the growth and development of Cervus canadensis antler velvet.