Abstract: neutral protease productwith an activity of 8000 u/g was used in the experiment. A basal diet without exogenous enzyme inclusion and four test diets adding 0.5‰, 1‰, 2‰ and 3‰ of the enzyme product respectivelywere prepared to feed five triplicate groups of fish with an initial average body weight of (3.03 ±0.04) g. The feeding trial was conducted in 15 re circulating tank systems (80L each) at a controlled water temperature of 25 ±0.5 ℃ and lasted for eight weeks. At the end of eightweeks, the weight gain of fish fed a diet with 0.5‰ of enzyme product showed no significant difference with that of fish fed basal diet (p >0.05). When fish fed a diet with 1‰ of enzyme product, the weight gain increased significantly (p 0.05). However, the apparent digestibility of dietary protein of fish fed four test dietswere significantly higher than that of fish fed the basal diet (p <0.05). The hepato-pancreas protease activity increased with increasing dietary supplementing the enzyme product up to 1‰, but above this level, it appeared to keep stable. In conclusion, under the condition of this experiment, adding 1‰ -3‰ neutral protease product to fingerling black carp diet could promote feed ingest and digest capacity of dietary protein, and as a result, improve fish growthand feed conversion.