Abstract: The entrainment and mixing process characterizes the interaction between cloud and ambient air, which is one of the most uncertain processes in cloud physics and dynamics. The entrainment and mixing process affects the formation of warm cloud precipitation, the evaluation of indirect effects of aerosols, and feedback between cloud and climate. This article summarizes the definition and classification of different entrainment-mixing mechanisms, the effects on the physical and optical properties of cloud and precipitation, and the quantitative description and parameterization of the entrainment-mixing process. Difficulties and future perspectives of the research on the entrainment and mixing process are also pointed out.