Objective: Multiple and overlapping diagnoses of personality disorders (PDs) have been a major obstacle in clinical practice and research. This study aims to investigate the comorbidity of PDs in a sample of a high-risk clinical population. We propose a diagnostic model to address this critical issue. Methods: The sample population included 982 PD patients. The PD diagnoses were concluded based on self-reported and face-to-face interviews. To address the issue of overlapping PD diagnoses, we defined the criteria for clinically distinguishing principal and subordinate PDs, and determined the frequency of each condition. Results: Diagnostic overlap among PDs was quite common across all categories. Of all 982 PD patients, 436 (44.4%) met the criteria for more than one PD. In terms of specific PD diagnoses, the comorbidity rate of each PD was nearly 47.1-74.7%. The principal and subordinate PDs were distinguished accordingly. Avoidant, obsessive-compulsive, and borderline PD remain the most prevalent types of principal PD in this clinical population. Conclusions: The principal/subordinate model may be one strategy of resolving the issue of PD comorbidity in Chinese clinical settings.