The pen shell is a large, fan-shaped bivalve that is widely distributed in the Indian and western Pacific oceans. However, little is known about the molecular regulation of its gonad development. The (wingless-type MMTV integration site family, member 4) gene, a member of the family, encodes a growth factor that plays an important role in gonad differentiation and development. In this study, the complete cDNA sequence of ovary by homology-based cloning and rapid amplification of cDNA ends techniques. The full-length cDNA sequence of was 1493 bp long and included an open reading frame of 1074 bp encoding a 357-amino acid protein with a predicted molecular weight of 39.5 kD and a theoretical isoelectric point of 8.94. Multiple alignment and phylogenetic analysis of wnt proteins showed that the wnt4 sequence contained conserved domains of the wnt family. In the phylogenetic analysis, the Chlamys farreri and lower similarity to the wnts of echinoderms, amphibians, and mammals. Quantitative real-time polymerase chain reaction analysis revealed that transcripts were present at higher levels in the female mantle and gonad of wnt4 transcripts was related to gonad maturity, and the transcription of was significantly ovary-predominant during the entire reproductive cycle. These patterns of transcription suggested that A. pectinata. During the early larval development stage of was detected in early embryogenesis (morula stage and gastrula stage), when it was 500 times that in adults, and then the transcript level fell sharply during the trochophore and D-shaped stages. Therefore, wnt4 may be involved in the formation of certain organs in the stages of early larval development. When the sex steroid estradiol-17 through feedback regulation ( treatment significantly induced transcription of , regulated by estradiol-17, is involved in a variety of biological processes in different tissues, especially during early embryogenesis and gonad development. Further research is required to verify whether the transcript level of can be used as an index of testis development.