Objective:To explore the mediating effect of clinical nurses' moral sensitivity between moral dilemma and professional identity.Methods:A total of 349 clinical nurses from Beijing Hospital were selected as subjects in May 2023 by the convenient sampling method. Nurses were investigated by general data questionnaire, Nurses Professional Identity Scale, Moral Distress Scale-Revised Version into Chinese (MDS-R-CV) and Moral Sensitivity Questionnaire-Revised Version into Chinese (MSQR-CV). Spearman correlation analysis was used to explore the correlation between clinical nurses' professional identity, moral dilemma and moral sensitivity. AMOS 26.0 statistical software was used to establish a mediating effect model and Bootstrap method was used to test the mediating effect.Results:A total of 349 questionnaires were collected, and after excluding questionnaires with a response time of less than 3 minutes, 341 valid questionnaires remained. The professional identity score of 341 clinical nurses was (109.19±21.03), the total score of moral dilemma was 45.00 (22.50, 85.00) and the total score of moral sensitivity was (42.61±6.46). The results of correlation analysis showed that the moral dilemma of clinical nurses was negatively correlated with moral sensitivity and professional identity ( P<0.05), and moral sensitivity was positively correlated with professional identity ( P<0.01). The mediating effect analysis showed that nurses' moral sensitivity played a partial mediating role in moral dilemma and professional identity, and the effect ratio was 14.43%. Conclusions:The moral sensitivity of clinical nurses plays a partial mediating role in moral dilemmas and professional identity. It is necessary to improve the moral sensitivity of clinical nurses, alleviate moral dilemmas and enhance professional identity, in order to provide high-quality nursing services for patients.