The species and vertical movement pattern of bacteria was studied in shrimp-cultured saline-alkaline pond in Tianjin.The results were as following:the amount of bacteria remained between 2.4×10 3 and 8.5×10 5 cfu/mL,the amount of Vibrio remained between 1.75×10 2and 2.3×10 5 cfu/mL,the amount of bacteria and Vibrio got to the peak in August and September,respectively.The amount of denitrifying bacteria remained between 3.4×10 4and 2.8×10 5 cfu/mL,the amount of sulfate-reducing bacteria remained between 2.9×10 2 and 7.5×10 4cfu/mL,and the amount of ammonifying bacterium remained between 1.2×10 2 and 7.0×10 4cfu/mL.There were 13 kinds of bacteria were examined in the shrimp-cultured pond.Vibrio,Alcaligenes and Corynebacterium were the mainly species in the earlier period,and Alcaligenes,Vibrio,Aeromonas and Enterobacteriaceae were the mainly species in the intermediate period,and Vibrion,Aeromonas and Cytophaga were the mainly species in the later period.The bacteria diversity index were highest in July and lowest in September.