Abstract: We chose Nile tilapia Oreochromis niloticus juvenile from Shanghai, Shandong and Hebei strains, which were chronically acclimated, as experimental groups, and studied their survival rate and average growth rate in net cage under different salinity waters (0, 15, 20), NaHCO₃ alkalinity waters (1 g·L^-1, 2 g·L^-1, 3 g·L^-1), and salinity-alkalinity waters (15, 1 g·L^-1; 15, 2 g ·L^-1; 15, 3 g·L^-1; 20, 1 g·L^-1; 20, 2 g·L^-1; 20, 3 g·L^-1). The 62 days experiments show that there is no significant difference in the survival rate among three strains under different salinities, alkalinities and salinity-alkalinity waters (P>0.05), while there is significant difference in average growth rate (P < 0.05). The average growth rate of three strains roughly tend to decline with increasing salinity and alkalinity, while the growth rate of salinity-alkalinity group increases slower than those of treated with salinity and alkalinity. Besides, Shanghai, Shandong and Hebei strains show some relative growth advantages in different salinity and alkalinity gradients, respectively. The study provides some basic data for determination of optimum growth salinity-alkalinity and for selection of Nile tilapia strain.