Objective   To explore social anxiety and its related factors in medical university students.    Methods   309 medical students were assessed with interaction anxiousness scale (IAS)，social avoidance and distress scale（SADS），eysenck personality questionnaire (EPQ) and self-esteem scale (SES).    Results   15.21% of subjects showed moderate levels of  social anxiety.The IAS and SADS scores in the female were higher than the male（P0.05）.Major and age also influenced significantly the anxiety levels （P0.01

P0.05）. Social anxiety level was significantly associated with self-esteem

EPQ-E and EPQ-N ( P0.01) . Social anxiety was positively correlated with self-esteem and EPQ-E

and negatively correlated with EPQ-N(r=-0.515

P0.01). In a hierarchical regression

the four factors (SADS

EPQ-E

EPQ-N and self-esteem)significantly predicted variance in the measurement of social anxiety.    Conclusion   The training on interpersonal communication skills of medical students

including particularly self-evaluation

cognitive transformation and behavioral training

should be developed effectively.