Japanese Grenadier Anchovy (Coilia nasus) in the Yangtze River has migratory and sedentary ecotypes, and spawning migration is a major phenotypic difference between the two groups. In order to explore whether olfactory receptor genes are involved in the process of spawning migration in C. nasus, the mor-4k13 gene encoding olfactory receptor was cloned from olfactory rosette RNA of migratory C. nasus using RACE. The mor-4k13 gene was 1 098 bp in length with an open reading frame of 963 bp which encoded 320 amino acid residues, and this gene was single exon (Fig. 2). Gene structure analysis indicated that this protein had seven hydrophobic and alpha helix transmembrane structure, belonging to the G-protein-coupled receptor superfamily (Fig. 4), and had two ligands including cholesterol and oleic acid. The homology between mor-4k13 protein of C. nasus and OR protein of other reported fishes ranged from 40% to 68%, and the homology of closely related species Atlantic Herring (Clupea harengus) was 68% (Table 2). The result based on qRT-PCR among 10 tissues and organs of the settlement population revealed that the mor-4k13 gene was expressed strongly in female olfactory rosette and ovary. Its expression in female olfactory rosette and gonad was high, but weak in muscle, eyes, stomach, liver and gills, and almost no expression was found in the heart (Fig. 5). In addition, the overall expression of the mor-4k13 gene in migratory C. nasus olfactory rosette was higher than in the sedentary group. In the migratory population, its expression in male olfactory rosette was 3 times higher than in female olfactory rosette (Fig. 6). In summary, the mor-4k13 gene not only was related to olfactory function, but also participated in gonadal development or associated with reproductive migration, and there existed gender gap in the olfactory ability.