Objective To investigate the levels of perceived security,fear of evaluation and ambivalence over emotional expression among nurses，and to explore the mediating effect of perceived security on the relationship between fear of evaluation and ambivalence over emotional expression. Methods A total of 161 nurses were investigated using the Security Questionnaire (SQ), Fear of Positive Evaluation Scale (FPES), Brief Fear of Negative Evaluation Scale (BFNES) and Ambivalence Over Emotional Expression Questionnaire (AEEQ-C). Results The total score of SQ, FPES, BFNES and AEEQ-C was 53.84±12.44, 31.78±15.27, 24.89±7.48, and 96.26±23.20 respectively.Perceived security completely mediated the relationship between fear of positive evaluation and ambivalence over emotional expression, and partially mediated the relationship between fear of negative evaluation and ambivalence over emotional expression. Conclusion Perceived security and ambivalence over emotional expression of nurses are at moderate level, and they have fear of positive and negative evaluation. Perceived security mediates the relationship between fear of evaluation and ambivalence over emotional expression. Promoting perceived security and facing negative evaluation correctly can mitigate the impact of fear of evaluation on ambivalence over emotional expression.