Abstract: At present CALPHAD technique is not capable of predicting even whether there exists intermediate compound and much more predicting nothing about its formula and the number of intermediate compounds. To predict the existence or not, formula and number of intermediate compounds, a new approach called the phase diagram evaluation by pattern recognition (PDEPR for short) has been proposed. The micro-para meters, such as radius and electronegativity of element were used as original features and then they were trans formed and spanned to the different features in multi-dimensional space. Then a set of classifying functions was attained to predict the intermediate compounds in the systems of the REX₂-AX (RE:rare earths; A:Li, Na, K, Rb, Cs; X:F, Cl, Br, I).