The purpose of this study was to introduce the major concepts of the Psychoanalytic object relation theory and how these concepts applicate to therapy. To this purpose, the concepts of the self representation, object representation, self structure, internalization mechanism(incorporation, introjection and identification) and defense mechanism(splitting, projective identification) were discussed. Moreover, Winnicott's concepts of the good enough mothering, holding, true self, false self and Mahler's concepts of the developmental stage(Autism, symbiosis, separartion-individuation) were explained. Finally, a related case was introduced and discussed.