Abstract: The self-expansion questionnaire, the Chinese adult self-concept scale, the neurotic subscale of the Big Five Personality Scale and the relationship stability scale are used to investigate 2, 133 college students who are in love to explore the influence of relational self-expansion on the stability of their romantic relationship and the mediating effect of general self-concept and the moderating effect of neuroticism. It is found that general self-concept plays a significant mediating role in the influence of relationship self-expansion on relationship stability and that the first-half path of the mediating role of general self-concept and the direct effect of relationship self-expansion on relationship stability are moderated by neuroticism. In conclusion, the mediating effect of general self-concept on relationship stability is partial and the mediating effect of general self-concept is more significant in the low neurotic group; the predictive effect of relationship self-expansion on relationship stability increases with the neuroticism level.