The impact of water temperature (24, 27, 30 and 33℃) and salinity (15, 20, 25, 30 and 33) on oxygen consumption (OCR) and ammonium excretion rate (AER) of ♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus hybrid grouper juveniles (9.39 ± 0.07 g) were investigated under the fed and un-fed conditions. The results showed that the OCR and AER were significantly ( P < 0.05) affected by temperature and salinity under both fed and un-fed conditions. When temperature was 24–33℃, the OCR and AER of fed hybrid grouper juveniles were 85.68%–129.52% and 125.78%–287.63%, respectively, higher than those of un-fed hybrid grouper juveniles. The O/N ratio, protein use ( P u), Q 10(respiration) and Q 10(excretion) of fed hybrid grouper juveniles were 14.43–24.01, 28.35% – 48.48%, 1.69 and 3.01, respectively. The O/N ratio, P u, Q 10(respiration), Q 10(excretion) of un-fed hybrid grouper juveniles were 20.39 – 31.79, 22.16% – 34.34%, 1.23 and 1.17, respectively. When salinity was 15–33, the OCR and AER of fed hybrid grouper juveniles increased by 87.42% – 116.85% and 215.38% – 353.57%, respectively, over those of un-fed hybrid grouper juveniles. The O/N ratio and P u of fed hybrid grouper juveniles were 14.48 – 17.78, 39.36% – 49.43%, respectively. The O/N ratio and P u of un-fed hybrid grouper juveniles were 20.39 – 31.79 and 22.16% – 34.34%, respectively. The specific dynamic action (SDA) of hybrid grouper juveniles was mainly related to protein metabolism. The results had a guiding significance to the large-scale intensive aquaculture of hybrid grouper juveniles.