To understand the potential mechanisms of the Wnt4 gene at different development stages and adult tissues of the mussel Mytilus coruscus, the Wnt4 gene was cloned by RACE technique. The full length of Wnt4 gene was 3 342 bp with 1 074 bp of open reading frame (ORF) encoding 357 amino acids. Homologous analysis of the amino acids of Wnt4 gene in M. coruscus shared high similarity with Homo sapiens (61%), Mus musculus (61%), Paracentrotus lividus (61%), Chlamys farreri (71%) and Crassostrea gigas (76%). qRT-PCR showed that Wnt4 mRNA expression was detected in all tissues (mantle, adductor muscle, gill, foot, digestive gland, male and female gonad) and the highest expression was found in mantle, indicating that Wnt4 gene may play an important role in shell formation. Relative gene expression of Wnt4 during larval development stages including trochophore, D-shaped, umbo, pediveliger and the juvenile stage was also detected. The Wnt4 mRNA was highest expressed in umbo stage larvae, suggesting that Wnt4 gene may participate in the process of shell morphological structure change and certain organ formation and development. Taken together, the finding provides a new insight into investigating the function of Wnt gene family.