Abstract: sCAP could stimulate heart movement and contraction of muscle and fallopian tube, enhance posterior bowel contraction and participate in biological molting. This study identified the sCAP gene (GenBank accession No. MG779491) from Sepiella japonica as SjsCAP. We cloned a 696 bp full-length cDNA sequence of SjsCAP gene by RT-PCR and RACE techniques including 111 bp 5′ untranslated region (UTR), 324 bp 3′UTR, and 261 bp open reading frame (ORF) encoding a protein with 86 amino acids. The molecular weight of the protein was 9.331 kD and its pI was 8.52. The prediction of signal peptides and transmembrane domain indicated that SjsCAP might play an important role in extracellular. The protein is hydrophilic. Phylogenetics analysis based on SjsCAP amino acid sequences demonstrated that S. japonica has the closest relationship with Sepia officinalis with a 90% similarity. Expression analysis of SjsCAP gene in male and female individuals showed that it mainly expressed in optic lobe and also has the high expression in the brain. The expression level in male was obviously higher than that of female cuttlefish. The results of in situ hybridization assay showed that significant positive hybridization signals were detected in the optic lobe of the brain tissue of S. japonica, the vertical lobe, subvertical lobe, peduncle lobe, dorsolateral lobe of the esophageal nerve mass, and optic gland. These results provide some theoretical basis for genetic resource conservation and development of S. japonica.