Abstract: Objective To investigate social undermining, rumination and turnover intention in ICU nurses of tertiary hospital, and explore their relationship in order to provide reference for the management of clinical nurses. Methods Qualified 528 ICU nurses were recruited from 4 tertiary hospitals in Shaanxi Province by convenience sampling between February and July 2017. Social Undermining Scale, Chinese version of Nolen-Hoeksema Ruminative Responses Scale and Turnover Intention Scale were used to collect data. Pearson correlation coefficient was used to analyze the correlation and Amos 17.0 software was used to test the fitting of structural equation model diagram. Results The scores of social undermining was (43.63±6.22), with (22.37±5.14) in supervisor subscale, and (21.26±4.83) in coworker subscale. The scores of rumination and turnover intention were (44.83±9.32) and (17.14±5.10) respectively, among which 14.4% participants had very high turnover intention, and 49.4% had high turnover intention. The pairwise correlation analysis of social undermining, rumination and turnover intention had statistical significance (P<0.01). Rumination exerted a partial mediating effect between social undermining and turnover intention, with the mediating effect of 0.27, which accounted for 52.9% for the total effect. Conclusion ICU managers should recognize the existence of social undermining, advocate sincere cooperative colleague relationship, create a good environment, pay attention to the stress relief and psychological counseling work of ICU nurses, so as to reduce their turnover intention and improve the quality of clinical nursing services.