| Galectin is a pattern recognition protein, which is mainly involved in immune recognition, cell phagocytosis, and immune elimination in invertebrate. Taking the Sinonovacula constricta that important tidal flat cultured shellfish in China as the research object, the galectin gene from Sinonovacula constricta (named ScGL) was cloned using RACE method. The full length cDNA sequence of ScGL was 1282 bp, which contains a 35 bp 5'UTR, 329 bp 3'UTR and 918 bp open reading frame (ORF) that encoded 305 amino acid residues. Analysis of amino acid sequences showed that ScGL lacks a transmembrane domain and contains 2 CRD unlike the galectin contains one CRD that had been identified in Sinonovacula constricta. Multiple sequence alignment and phylogenetic analysis showed that ScGL shared a hige degree of conservatism with galectin of other species and had the highest identity with Ruditapes philippinesis (65%), 39.74% and 44.76% identical with two galectins reported in the Sinonovacula constricta. ScGL was expressed in inclusion bodies with a calculated molecular mass of 34.4 ku. Quantitative real-time PCR detection results indicated that the ScGL gene were expressed widely in gill, intestine, labial palpus, mantle, exhalent siphon, inhalent siphon, foot and visceral mass, the highest expression level was observed in the intestinal, visceral mass, labial palpus and foot, and the lowest expression in the exhalent siphon, Inhalent siphon. After the Staphylococcus aureus challenge, the expression of ScGL in the digestive gland was significantly up-regulated at 3 hpi and 48 hpi (hours past infection), upon Vibrio anguillarum and Staphylococcus aureus challenge, the expression of ScGL was significantly up-regulated in the gill was respectively up-regulated at 6 hpi and 48 hpi. The result suggests that ScGL might participate in the innate immune response of Sinonovacula constricta triggered by pathogens. The study provides the good foundation for further research of the ScGL in Sinonovacula constricta immunity.