OBJECTIVE: To investigate whether there is a difference in the personality traits and related personality traits between the only child and non-only child among college students. Methods: Sophomores from three universities in Jiangsu province were selected and surveyed using PID-5 and general data sheets. Results: There were no statistically significant differences between the only children and non-only children in the five personality dimensions of negative emotions, separation, confrontation, disinhibition, and psychosis (t=-0.374~0.140,p>0.05). In terms of intimate personality traits, the difference between the only child and non-only child is statistically significant (t=-0.736,p<0.05). In terms of other 24 personality traits, the difference between the only child and non-only child is not statistically significant (t=-2.525~1.095,p>0.05). Conclusion: There is a difference between the only child and the non-only child in the personality trait of avoiding intimacy. Suggested that psychological education in colleges and universities should pay attention to students' interpersonal communication and give students more encouragement and support.