Objectives: In the exploration of human unconsciousness, Sadism and Masochism has already become one kind of object relation pattern, which is not only concerned with patients’ sexual psychology and sexual behaviour , but also expressed in all life profiles of the persons involved. Probably we can even infer that the pattern of Sadism and Masochism itself is just an important composition of the collective unconsciousness of human being. Methods: Using single case study design, a man with both sadistic and masochistic symptoms was administered 125 sessions of psychodynamic therapy systematically. During the course of therapy, the therapist was under the systematic case supervision from both foreign and Chinese experienced experts. Results: Through deep analytic therapy, the hypothesis mentioned above was proved. The patient still perform the circle of Sadism and Masochism compulsively and repeatedly in his object relations even after his sadistic sexual behavior disappeared. Conclusions: Sadomasochism is a kind of being for the patient. According to my analysis, it seems that Sadomasochism pattern(or tendency) would influence each of us, and this contradictory and vibrated force would go along with us in a lifetime. Sometimes it would be a kind of motivation for advance and sometimes a kind of restriction for the mind.