Differential expression of genes is crucial to growth and development of fish.To select the appropriate genes for gene normalization during Cynoglossus semilaevis early developmental process,eight candidate reference genes(ACTB,B2 M,EF1 A,GADPH,RPL7,TUBA,UBCE and 18S) were tested for their adequacy by using quantitative real-time PCR.The results showed that the expression of all the examined genes exhibited tissue dependent variations in the mature C.semilaevis.EF1 A was listed as the most stable reference among the 14 tissues by Ref Finder.Furthermore,the recommended comprehensive ranking of the stability determined by Ref Finder showed that 18 S was the most stable gene during the early developmental stages(from oosphere to 90 days old) in this study.However,when divided the Ct value data of the above mentioned early developmental stages into two separate periods(embryo and post-hatching periods),TUBA and 18 S represented the most stable references of these two developmental periods,respectively.Consequently,the reference gene should be carefully and accurately chosen even for studies of the same species at various developmental processes.The relevant data may help in selecting appropriate reference genes for m RNA expression analysis,and is of great value in the studies of fish growth and development. Differential expression of genes is crucial to growth and development of fish. To select the appropriate genes for gene normalization during Cynoglossus semilaevis early developmental process, eight candidate reference genes (ACTB, B2 M, EF1 A, GADPH, RPL7, TUBA, UBCE and 18S ) were tested for their adequacy by using quantitative real-time PCR. The results showed that the expression of all the examined genes cloth tissue dependent variations in the mature C. semilaevis. EF1 A was listed as the most stable reference among the 14 tissues by Ref Finder.Furthermore, the recommended comprehensive ranking of the stability determined by Ref Finder showed that 18 S was the most stable gene during the early developmental stages (from oosphere to 90 days old) in this study. However, when divided the Ct value data of the above mentioned early developmental stages into two separate periods (embryo and post-hatching periods), TUBA and 18 S represented the most stable references of these two developmental periods, respectively.Consequently, the reference gene should be carefully and accurately chosen even for studies of the same species at various developmental processes. the relevant data may help in selecting an appropriate reference genes for m RNA expression analysis, and is of great value in the studies of fish growth and development.