Abstract: To investigate the effect of locomotion and feeding on the metabolic mode of juvenile lenok, Brachymystax lenok (Pallas) under different water temperatures, the preexercise oxygen consumption rate (MO_2p), active oxygen consumption rate (MO_2a), metabolic scope (MS), critical swimming speed (U_C) and swimming metabolic rate of both fasting and fed fish were measured at five temperature levels (4 ℃, 8 ℃, 12 ℃, 16 ℃ and 20 ℃) and ten flow velocities with saturated dissolved oxygen (>8.0 mg·L^-1). The results showed that the MO_2p and MO_2a  of the feeding group were significantly higher (P<0.05) than the fasting group under different temperatures, and the increases in MO_2p and MO_2a at 4 ℃, 8 ℃, 12 ℃, 16 ℃and 20 ℃ were 15%, 47%, 30%, 43% and 8%, and 12%, 23%, 21%, 36% and 7%， respectively. No significant differences were observed for U_C  and MS between the fasting and the feeding groups (P>0.05), but the MS showed a trend of decline with increase in water temperature. Swimming metabolic rate of fish was increased with increasing the flow velocity, and further increase of flow velocity resulted in a decline in swimming metabolic rate, and the swimming metabolic rate of the feeding group was significantly higher than that of the fasting group (P<0.05). The metabolic rate increased with increasing the swimming speed up to 70% U_C, and then decreased with increasing the swimming speed up to U_C. It was concluded that, under certain temperature, the maximum metabolic rate was induced by exercise and feeding; the metabolic rate exhibited the additive metabolic mode before increasing to the maximum and thereafter, the metabolic rate induced by feeding reduced with decreasing the swimming metabolic rate, exhibiting the locomotion prioritized mode.