Abstract: Crayfish is an important aquaculture animal and a good model for the research of crustacean diseases and immunity. When studying the function of different tissues and the effects of pathogen infection, it is necessary to know the number of cells in the tissue. However, most of the cell counting methods are only applicable to single-cell suspensions, which are not suitable for solid tissues. In this study, we established a method to determine the cell number in the tissues of Cherax quadricarinatus basing on quantitative analysis of gene copy number. Firstly, partial DNA sequences of two genes, beta-actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were cloned. For qPCR analysis, one primer was designed in exon and the other was designed in intron. Secondly, the qPCR melt curves were analyzed for both genes, and beta-actin was chosen as the target gene. Crayfish hemocytes were counted by cell counter and used as the standard samples for qPCR analysis. The results showed that the Ct value of beta-actin gene has a linear correlation with the number (N) of hemocytes in range of 1×10¹-1×10⁵cells. The linear regression equation is Ct=38.30-3.37lg (N). Finally, to determine the cell number in gill and hepatopancreas, DNA was extracted from these tissues. The beta-actin gene was analyzed by qPCR, and the cell numbers were calculated with the formula. The number of cells in gill was (1.8-2.2)×10⁵ cells/mg tissue, and the number in hepatopancreas was (5.5-6.0)×10⁵ cells/mg tissue. This simple and high-throughput quantitative method greatly facilitates the cell counting in solid tissues.