Full length cDNA sequences of gonadotropin hormone β subunits were cloned from the pituitary of Oplegnathus fasciatus by homology cloning and RACE techniques.The expression of GtHβ mRNA was analysed in different tissues and different ovarian development stages of pituitary,ovary,and brain.The FSH cDNA sequence is 554 bp and its open reading frame is 363 bp,which encoded a precursor protein of 120 amino acids preceded by a signal peptide of 18 amino acids residues.The LH cDNA sequence is 857 bp and its open reading frame is 450 bp,which encoded a precursor protein of 149 amino acids preceded by a signal peptide of 24 amino acids residues.Both of the putative peptide of FSH and LH contained 12 cysteine residues and 1 N-glycosylation sites residues.Moreover,there was a special area of Cys-Ser-Gly-His(CSGH)in the middle of 4 and 5 cysteine of LH.Sequences comparison and phylogenetic analysis showed that the O.fasciatus FSH and LH had the close relationship with Perciformes.The Real-time Quantitative PCR results suggested that the expression levels of FSH and LH mRNA were the highest in pituitary,followed by ovary.The FSH mRNA was not found in kidney and head kidney and the LH mRNA was not found in Head kidney.The GtHβ expression level in the reproductive cycle showed that the level of pituitary FSH mRNA was maximum in the Ⅳ ovarian development stage and the LH mRNA was maximum in the Ⅴ ovarian development stage.In ovary,the level of FSH mRNA was the lowest in the Ⅴ ovarian development stage,however,the LH mRNA was maximum in the Ⅴovarian development stage.Both of the brain FSH and LH mRNA were the lowest in theⅤovarian development stage.The hormone analysis indicated that the concentration of FSH was maximum in the Ⅳovarian development stage in serum,but the concentration of LH was maximum in the Ⅴ ovarian development stage in serum.The content of FSH and LH in serum showed a consistent trend of regular changes with the level of FSH mRNA and LH mRNA in pituitary.The research is beneficial to the technique of artificial breeding in O. fasciatus.and provides a certain reference value to the reproductive regulation of O. fasciatus.