Enzymes are organic catalysts, that can Trigger or accelerate chemical reactions and covert One or more organic compounds to organic production. This study was designed to investigate the influence of supplementing multi-enzyme on liver biochemical parameters (LDH, ALP, AST, and ALT) and performance parameters of rainbow trout growers (150 ± 5 g). The multi-enzyme were incorporated into a commercial pellet ration to constitute three experimental diets containing 500, 1000, 1500 gram multi-enzyme per one ton feed intake, while a fourth diet without the multi-enzyme supplement served as the control diet. Fish were sampled at 10, 20, 30 and 40 days after commencement of the feeding trial to determine feed conversion ratio (FCR), weight and length rate and survival rate. At the end of the raising period 50 fish from each and finally 200 fish were selected randomly and blood sampling performed and then liver biochemical parameters were measured. Results of our study indicated that effect of different supplementing multi-enzyme levels on feed conversion ratio (FCR), weight and length rate and survival rate, there was not any meaning relation in dose rates (p>0.05). In this study, 1500 g/ton group displayed significantly reduction (P>0.05) AST levels compared to 500 and 1000 g/ton groups. The result showed that 500g/ton group displayed significantly reduction (P>0.05) ALT levels compared to control group. 500, 1000 and 1500g/ton groups displayed significantly reduction (P>0.05) LDH levels compared to control group. Also, There was no meaningful relationship between multi-enzyme level in ration ALP levels (P>0.05). According to this study, the use of multi-enzymes, can reduced amounts of ALT, AST and LDH levels in rainbow trout growers. Therefore, taking these supplements can be recommended, in considered values for use in aquaculture.