Abstract Compared with normal children, leftbehind children who experience parent child separation receive less care and attention from their parents, and are more likely to have cognitive and behavioral adaptation problems, thus leading to an elevated risk of depression. The study systematically examines the effects of parent child separation type, separation duration and separation age on depression among left-behind children. Attachment theory, interpersonal relationship, theory attribution theory and behavior theory have been used to explain how parentchild separation influences depression among left-behind children, so as to provide reference for relevant research and mental health education for left-behind children.