Objective To explore the mediating effect of psychological stress and resilience on sleep conditions and working stress among the officers and soldiers during major tasks. Methods Psychological stress evaluating test (PSET), perceived stress scale (PSS), Pittsburgh sleep quality index (PSQI), and Connor-Davidson resilience scale (CD-RISC) were used to survey 464 officers and soldiers who took part in major tasks during June 2019 and June 2020. The subjects were assigned into control group (n=136) and somnipathy group (n=328, including light, moderate and severe subgroups) according to their sleep conditions, and also into low-resilience (n=95) or high-resilience (n=369) groups based on their scores of psychological resilience. Logistic regression analysis was employed to analyze the related factors for sleep disorders, and Pearson correlation analysis was adopted to investigate the correlation of psychological stress and resilience with sleep quality as well as severity of working stress, so as to determine the mediating effect of the former 2 factors on the latter 2. Result After 2 and 6 cases were excluded due to incomplete data from the somnipathy and control group respectively, there were finally 456 cases subjected (134 and 322 cases respectively). The age, numbers of violence witnessed, and PSS and PSET scores were older, larger and higher, while the CD-RISC score was lower in the somnipathy group than the control group (P