An outbreak of coronavirus disease 2019 (COVID-19) is a public health emergency of international concern and poses a big challenge to medical staff and general public. The aim is to investigate psychological impact of COVID-19 epidemic on medical staff in different working posts in China, and to explore the correlation between psychological disorder and the exposure to COVID-19. A multicenter WeChat-based online survey was conducted among medical staff in China between 26 February and 3 March 2020. Medical staff deployed to Hubei province from other provinces and medical staffs in different posts outside Hubei were selected to represent diverse exposure intensities to the threat of COVID-19. Anxiety, depression, sleep quality, stress and resilience were evaluated using scales including GAD-7, PHQ-9, PSQI, PSS-14, and CD-RISC-10. Latent class analysis was performed to identify potential staff requiring psychological support. A total of 274 respondents were included, who serving at 4 posts as follows, staff backing Hubei province, isolation wards outside Hubei, fever clinic and infectious disease department, and other departments outside Hubei. The total scores of anxiety, depression, sleep quality and stress were statistically different among groups, meanwhile an increasing tendency of anxiety, depression and sleep quality scores with increasing risk of exposure to COVID-19 was found (p < 0.05). Subsequent post-hoc analysis indicated that the staff backing Hubei had higher scores of anxiety, depression, sleep quality and perceived stress (adjusted p < 0.05). The combined prevalence of anxiety, depression and insomnia of staff backing Hubei reached as high as 38%. Four-class latent class analysis showed 3 categories of population (69.4%) may need psychological support. High prevalence of anxiety, depression and insomnia exist in medical staff related to COVID-19. The higher the probability and intensity of exposure to COVID-19 patients, the greater the risk that medical staff will suffer from mental disorders, suggesting continuous and proper psychiatric intervention are needed.