Abstract: To evaluate the effects of replacement of fishmeal with cottonseed meal on growth, feed utilization, hematological physiology, and body composition of juvenile grass carp mean initial body weight of (100.00.29) g, seven isonitrogenous and isoenergetic diets (C, R20, R40, R60, R80, R90 and R100) containing graded levels of cottonseed meal (CSM) (replacing 0, 20%, 40%, 60%, 80%, 90%, and 100% FM protein by CSM protein) were fed to triplicate groups of fish for 8 weeks. The results showed that the diets containing 60% of replacement levels significantly diminished the specific growth rate (SGR) of the fish compared with the non-replacing group (P0.05). The increased levels of CSM significantly decreased FE, PRE and ERE (P0.05), and the optimal replacement level by CSM was 43.3% protein. CSM had no significant effects on the ALT activity, AST activity or the content of TGy (P0.05). Moreover, the dietary CSM reduced the content of serum TCh, HDL-C and LDL-C, and the significant difference was observed when the replacement is 40% or more. The dietary CSM at all graded levels had significant effect on the water content of fish body (P0.05), but it did not regulate the content of protein or ash of the fish body. The role of diatery CSM in regulating the lipid and gross energy contents is concentration-dependent: R20 diet significantly increased them compared to the control group (P0.05); R100 diet significantly decreased them; (P0.05); R40, R60, R80, or R90 did not have significant effects.