The carbonation column used in manufacture of soda ash is not only a multiphase reactor but also a multistage crystallizer. The complex processes include chemical absorption，reactive precipitation，multiphase flow，heat and mass transfer，and other physico-chemical processes taking place in the column. Industrial application of a commercial software of model predictive control（MPC）for five groups of twenty-five carbonation columns in a soda plant was introduced in this paper. An MPC system，which was composed of nearly one hundred controlled variables，manipulated variables and disturbance variables，was developed to deal with the constrained multivariable control problem on-line of the carbonation columns. Industrial application results showed that the MPC software could ensure the best operation for a long time and realize the ultimate highest operation potential of the carbonation systems by reducing the consumption of materials，improving product quality，and minimizing operating cost.