Abstract: Personality disorders（PDs） have been argued by researchers and clinicians since the DSM’s first edition in USA. And the comorbidity of PDs’ became one specific focus of their attention, as DSM work group placed PDs on a separate axis in the third edition. The high levels of comorbidity among Axis-II and several explanative models were introduced in this article. Then reviews on what has been proposed to cope with this problem was also discussed systematically. In the end, opinions and suggestions on understanding of comorbidity and some relevant aspects were proposed

Key words: comorbidity, dimensional model, categorical method