Abstract: Luminescent bacteria test was applied to the detection of biological toxicity of hypochlorite treated ballast water.Simulated sea water was prepared and used in the experiments.Artificially incubated aquatic insect (the “brine insect”) was added in the ballast water as living organisms and photobacterium phosphoreum T3 spp was used as the luminescent bacteria in the detection.Samples of ballast water ware treated individually with hypochlorite having different concentration of available chlorine (5,10,20 mg·L-1) and for different time periods (2,6,16 and 24 h),during which the available chlorine was determined every 6 h interval and its concentration kept at the prescribed values.At the end of treatment,remnant of the insect was removed by mesh filter,and the remaining chlorine was rendered inactive by reduction with sodium thiosulfate.An aliquat of the solution was taken and its luminescence intensity were determined by the standard method in GB/T 15441-1995.As shown by experimental results,low biological toxicity was obtained when the hypochlorite treatment was performed with 10 mg·L-1 of available chlorine and for a period of less than 6 h.