Abstract: In recent years, researchers interested in the influence of family on the development of children, while foreign family researchers and therapists began pay attention to the study of psychological separation. psychological separation is the process of individual separates from their family and develops their individuation psychologically. The article focuses on the definition of psychological separation, the theoretic background of psychological separation, which consists of Mahler’s developmental phases theory and Bowen’s systemic family theory, measurement of psychological separation，and conclusions of previous researches, expatiate the inspiration which psychological separation researches bring to our national family research and therapy, and prospect the research of future

Key words: psychological separation, developmental phases theory, family therapy theory, measurement