Colloidal particles in solution exhibit rich phase behaviors and behavior like big-atom. In the past decades, as modelling systems, colloids have been widely employed in the study of nucleation, crystallization, glass transition and melting. A number of advances have been achieved. These advances to a large extent extend and complete the understanding of various phase transitions. Recently, a number of active fields are emerging with colloidal model systems. In this review, the advances and the emerging fields are summarized. At the end, the potential directions and the challenges for future studies are suggested.