Abstract: Objective To explore the characteristics of defense mechanism in patients with obsessive-compulsive disorder(OCD).Methods Outpatients diagnosed as OCD were tested by Yale-Brown obsessive Compulsive Scale. Among them, 40 patients with score beyond or equal to 16 were selected as research group. 33 healthy individuals were selected as normal group. They were tested with Defense Style Questionnaire.Results ①The factor score of immature defense mechanisms in the OCD group is much higher than that in the normal group (P<0.01); the factor score of mature defense mechanisms in the OCD group is lower than that in the normal group (P<0.05); the factor score of middle defense mechanisms in the OCD group is much higher than that in the normal group (P<0.01). ②Passive aggression, acting out, splitting, regression, somatization in the immature defense mechanisms and relief, false altruism, isolation in the middle defense mechanisms are much more used by the OCD group than that in the normal group; but suppression and humor in the mature defense mechanisms are less used by the OCD group than that of the normal group(P<0.05 or P<0.01). ③Sublimation, suppression and consuming tendency are much more used in male patients than female ones in OCD group(P<0.05).Conclusion The patients with OCD tend to use the immature defense mechanisms and middle defense mechanisms, and there is some difference between male and female patients in using defense mechanisms.

Key words: obsessive-compulsive disorder, defense mechanism, Yale-Brown Obsessive Compulsive Scale, Defense Style Questionnaire