The lenok (Pallas) is one of the most important salmonid fish in northeast China. To date, no information on the optimal dietary protein and lipid levels of this species has been reported. A 10-week feeding trial with four dietary protein levels (40%, 45%, 50% and 55% crude protein) and two dietary lipid levels (8% and 16% crude lipid) was conducted to assess the dietary protein and lipid levels for the growth and of amino acids of juvenile lenok. The results showed that weight gain (WG), specific growth rate (SGR), condition factor (CF) and hepatosomatic index (HSI) were significantly affected by dietary protein and lipid levels (<0.05), and there were also significant interactions between these two factors (<0.05). WG, SGR, CF and HIS rose with increasing dietary protein levels at each lipid level, and decreased after that. The growth of fish fed the high-lipid level diet was significantly higher (<0.05) than that of fish fed the low-lipid level diet at 40% and 45% protein diet, whereas these values showed an opposite trend at 50% and 55% protein diet. Fish fed diets with low protein levels had the lowest survival levels of all groups. The lipid content of muscle increased significantly with increasing lipid levels (<0.05), while moisture, crude protein and ash content were not affected by dietary lipid level. The protein content of muscle increased significantly with increasing protein levels (<0.05), while lipid and ash content were not affected by dietary protein level. The lipid content of fish fed high-lipid level diets was significantly higher than that of fish fed lower-lipid level diets at each protein level. The protein content of fish fed diets 55P/8L and 55P/16L was significantly higher than that of fish fed in other groups. Seventeen amino acids were found in the muscle of fish. The percentages of total amino acids and the ratios of essential amino acids:total amino acids showed no significant difference among the treatments (>0.05). The content of the different amino acids was stable and the constitutional rate of the EAAs met Food and Agriculture Organization and World Health Organization standards. The results indicated that the optimum protein and lipid levels for the lenok were 50% and 8%, respectively; and the optimum protein:energy ratio for this species was 29.36 g/MJ.