Intertidal oyster (Saccostrea cucullata) is an important cultivated species and macro-fouling organism in the southeastern China Sea, and it is an important model organism for studies on shellfish physiology and marine ecology. Oxygen consumption rate and ammonia excretion rate are important parameters of shellfish physiology and metabolism, and can be measured as sensitive indicators of pollutant toxicity. However, little is known about the effects of environmental factors affect oxygen consumption rate and ammonia excretion rate of Saccostrea cucullata. The effects of water temperature (13, 18, 23, 28, 31, 34℃) and salinity (18, 23, 28, and 33) on oxygen consumption rate and ammonia excretion rate in Saccostrea cucullata were analyzed using experimental ecological methods. Oxygen consumption rate varied from 0.43 mg g^-1 h^-1 to 3.15 mg g^-1 h^-1 and the ammonia excretion rate varied from 72.62 μg g^-1 h^-1 to 1245.77 μg g^-1 h^-1 in different water temperature. Water temperature and salinity significantly affected oxygen consumption rate (F=60.440) and ammonia excretion rate (F=61.083); additionally, the combination of water temperature and salinity affected oxygen consumption rate (F=4.907) and ammonia excretion rate F=11.412). Temperature varied from 13 to 31℃ and salinity varied from 18 to 28, and the relationship between oxygen consumption or ammonia excretion rate (Y) and temperature (T) and salinity (S) can be represented by the equation Y=a+bT+cS+dT×S. The relationship between oxygen consumption rate (Y) and water temperature (T) can be described by the regression equation:Y=ae^bT, where a ranges from 0.1378 to 0.2117, and b ranges from 0.0757 to 0.0912. The relationship between ammonia excretion rate (Y) and water temperature (T) can also be described by the regression equation:Y=ae^bT, where a ranges from 20.364 to 30.634, and b ranges from 0.1044 to 0.1341. The atomic ratio of O and N varied from 2.20 to 7.78, with a mean of 3.81 to maintain standard metabolism in Saccostrea cucullata.