Family separation is often presented as a problem in both research and practice of left-behind children. Focusing on separation itself and reflecting on the problem-oriented approach in left-behind children research， this paper clarifies the characteristics and types of parent-child separation. It emphasizes that rethinking family separation and targeted intervention based on the classification is the prerequisite and basis for social work intervention for left-behind children. Therefore， this study argues that attention should be given to different types of separation in past， present， and future practice. It advocates for viewing the family as a whole as the fundamental unit of analysis and intervention to explore the development of localization route of rural social work.