As the rapid development of diversified society puts forward higher requirements for people's adaptation, the stress and its detrimental effects on undergraduate students' physical?and?mental?health have received substantial attention. A large body of research has documented the negative association between stress and people’s sleep quality. The present study aimed to examine the relationship between stress and sleep quality among undergraduate students. Determining the roles of mediators in the relationship between stress and ' sleep quality among undergraduate students will be important to provide guidance for interventions to improve sleep quality. Response style theory points out that rumination refers to the tendency of the spontaneous and repeated thinking of negative events after experiencing stressful events.And there are substantial evidence that rumination is negatively correlated with sleep quality. The present study hypothesizes that rumination may play a mediating role between stress and sleep quality. In addition, Theoretical model of stress cognition believes that individuals in the stress context will reduce their ability to cope with stress and thus show reduced mental resilience. Moreover, studies have confirmed a significant positive relationship between mental resilience and sleep quality. So the present study hypothesizes that resilience may play a mediating role between stress and sleep quality. Meanwhile, studies showed that rumination could directly and negatively predict mental resilience. So the present study hypothesizes that rumination and mental toughness play a chain mediating role between stress and sleep quality. In a word, The purpose of this study was to test the hypothesis that rumination and resilience mediated stress to sleep quality and further develop the mechanism of stress to sleep quality among undergraduate students. The present study selected 684 undergraduate students((mean age = 20.26 years, SD = 1.08 ) from Wuhan, Jinan and Chengdu, who participated in this study and adopted Resilience Scale for Chinese Adolescents, Ruminative Responses Scale, Stress Scale for College Student and Pittsburgh Sleep Quality Index.The present study first calculated the descriptive statistics for the variables, then processed the associations among these variables in the SPSS 22.0 software, and finally conducted a follow-up structural equation modeling (SEM) using AMOS21.0. The result shows:(1) common method biases can be accepted in this study, and the correlation among stress, resilience, rumination and sleep quality are all significant; (2)stress, rumination, and resilience can all predict sleep quality significantly.(3)structural equation modeling indicates good fit : χ2=244.23, df=76, χ2/df=3.21, CFI=0.95, NFI=0.93, IFI=0.95, TLI=0.93, RMSEA=0.06. It shows that rumination and resilience can play mediating roles between stress and sleep quality respectively and rumination and resilience play the chain mediating effect in the relationship between stress and sleep quality. The mediating effect of rumination in the relationship between stress and sleep quality is 27%; The mediating effect of resilience in the relationship between stress and sleep quality is 26%; The chain mediating effect of rumination and resilience in the relationship between stress and sleep quality is 25%. In conclusion, stress not only has a direct effect on sleep quality among undergraduate students but also influences sleep quality by the chain mediating effect of rumination and resilience. This study also finds that the factor loading of sleep time, hypnotic drugs and sleep efficiency on sleep quality is less than 0.3, which is related to the life characteristics of contemporary undergraduate students.And the present study suggests researchers to do confirmatory factor analysis of Pittsburgh Sleep Quality Index before data analysis for the entire study. These findings in the present study contribute to understanding the mechanisms underlying the association between stress and sleep quality among undergraduate students and have important implications for interventions aimed at improving sleep quality among undergraduate students.