Abstract: This paper proposes a method for the analysis and selection of complicated system variables by applying pattern recognition technique. By means of this method, system modelling and control scheme can be simplified. As the demonstration of the method, pattern recognition is first applied to analysing the inherent laws of the complicated carbonation process. The quantity relation between the crystal quality and the temperature distribution has been found. On this basis, carbonation mechanism and system identification have been combined to establish the dynamic model of the carbonation process successfully.