Predicting the probability (ability) of materials to form expected regular atomistic arrangement (single crystal) is highly desired to judge the applicability of the newly designed materials, and a theoretical model is developed for this purpose. The model that has been proved successful in predicting the ability of single-component materials to form single crystals is further extended to two-component materials. The prediction can be easily implemented via common ab initio calculations, and may be widely used in general materials design.