Abstract: The optimal chelating conditions for compound amino acid in cottonseed meal and ferrous chloride were investigated by response surface methodology (RSM) . Quadratic orthogonal rotation combination design and response surface methodology were applied the chelated conditions by pH, temperatureand the mass ration of compound amino acid and ferrous chloride as independent variables, while taking the chelated percent as dependent variable in the experiment. The results showed that the optimal reaction conditions were pH 4.30, temperature 40℃, the mass ration of compound amino acid∶ferrous chloride 3.3∶1 (g∶g) . Under these conditions, chelating rate was 73.76%, closed to the predictive value of 74.06%.