Fermented soybean processing waste water was used as coagulant to produce tofu. On the basis of single factor experiments, the total acid of fermented soybean processing waste water, amount of fermented soybean processing waste water and the temperature of pointing soybean milk were main factors, taking the sensory evaluation score and springiness, and the coagulation conditions were optimized through response surface methodology. Results showed that the optimum coagulation parameters were as follows: the total acid of fermented soybean processing waste water 5.3 g/kg, the amount of fermented soybean processing waste water 29% and the temperature of pointing soymilk 76 ℃. Under these conditions,sensory evaluation score of tofu arrived at 76.20±0.36, springiness arrived at 0.95±0.01.