This experiment was conducted to study the effects of different energy-protein ratios (E/P) on growth performance, muscle composition, the activities of digestive enzymes and energy budget of Procambrus clarkii. Five kinds of semirefined experimental diets with different E/P yet the same crude protein (CP) content were compounded. The CP content in the diets was 35%, and the E/P were 32, 34, 36, 38 and 40 MJ/kg, respectively. The Procambrus clarkiis with an average body weight about (8.41±1.12) g were fed 60 days. The results showed that the survival rate, relative weight gain rate and relative growth rate all had the pattern of first increase and then decrease while the E/P increased, with the peaks showed at 36 MJ/kg, significantly higher than those in the other groups (P<0.05). However feed conversion ratio at 36 MJ/kg was significantly lower than that in the other groups. Different E/P did not have any significant effects on the contents of moisture, crude protein and ash (P>0.05). With E/P increasing, the crude lipid content slowly increased in the muscle. The Met and Arg contents in the E/P 36 MJ/kg group were significantly higher than those in the E/P 32 and 40 MJ/kg groups (P<0.05). With E/P increasing, the activities of cellulose, amylase and protease in the hepatopancreas and cellulose in intestinal tract took the pattern of first increase and then decrease, with the highest levels in E/P 36, 36, 36 and 34 MJ/kg groups, respectively. The amylase activity in the intestinal tract took the pattern of first decrease and then increase, the peak and valley values in E/P 36 and 40 MJ/kg groups, respectively (P<0.05). The activity of protease in the intestinal tract of different groups did not show any significant difference (P>0.05). With E/P increasing, the ingestion energy had the pattern of a decrease after an increase, the peaks, 52.63 and 51.19 KJ, in E/P 36 and 38 MJ/kg groups, were significantly higher than those in the other groups (P<0.05); the growth/ingestion energy, urinary/ingestion energy and feces/ingestion energy had the pattern of a decrease after an increase, while respiratory/ingestion energy and exuviae/ingestion energy were contrary. In conclusion, the optimum E/P in the diet for the Procambrus clarkii is a range of 34 to 36 MJ/kg.