Abstract: The tidal influence, monsoon, freshwater inputs and other environmental factors impact temperature and salinity in tidal zone where the macroalgae grown. The current study evaluated effects of temperature and salinity on the growth and photophysiological performance of macroalgae. Ulva prolifera were cultured in 4 conditions including the ambient condition (22℃ and 25 salinity), normal temperature and low salinity (22℃ and 15 salinity), low temperature and normal salinity (15℃ and 25 salinity) and low temperature and low salinity (15℃ and 15 salinity) for 6 days to measure the growth, chlorophyll content, chlorophyll fluorescence parameters, SOD activity and soluble protein content. Our results showed that temperature did not impact the growth of U. prolifera at low temperature, and that low salinity decreased the growth of U. prolifera at normal temperature, and that temperature slightly but not significantly mediated the growth of U. prolifera at low salinity, and that low temperature significantly reduced the growth of U. prolifera at normal salinity. Temperature but not salinity significantly impact the F_v/F_m. U. prolifera cultured in low temperature and low salinity condition showed higher F_v'/F_m', NPQ, SOD activity and soluble protein content.