Abstract: A useful strain W_2 was obtained from the activated sludge of a dye-house waste water disposal plant through separation and sieving,which was capable of decolorizing reactive dye Lanasol Blue 3B.The effect of strain W_2 on the discoloration of Lanasol Blue 3B at different temperature,duration of treatment,pH value, and quantity of inoculation was studied.The decolorization conditions of Lanasol Blue 3B dye wastewater by strain W_2 were optimized through experiments.