Abstract: It was investigated based on conductivities of reactive dyes solution in different conditions,including concentration of the reactive dyes, medium temperature and additives. Results showed that the conductivity of reactive dye solution was directly proportional to the dye concentration and medium temperature. A certain critical range was existed during the change of conductivity which the concentration dye of solution was 30 - 40 mmol/L and the temperature was about 50oC. The change rate of conductivity was different in or out of the range that mainly due to the aggregation of dyes leading to the inhibition of ionization in the condition of high concentration. It was probably raising the temperature was conducive to the disaggregation. The conductvities would decreasced when adding additives such as sodium sulfate todye solution becauce of common ion effect lead to the aggregation of dyes exacerbated. Howerver the conductivity of dye solution was increased when the concentration of sodium sulfate was less than 3 g/L. auxiliaries such as anionic surfactant had significant effect on improving the stability of dye solution at 50 oC.