Objective To identify potential ergonomic risk factors of works and quickly assess their risks of developing work-related musculoskeletal disorders (WMSDs) in the medical staff. Methods A total of 188 medical staff were selected as the research objects using a two-stage random sampling method. The method for the identification of musculoskeletal stress factors (PLIBEL) was used to analyze the adverse ergonomic factors in the work process, and the rapid entire body assessment (REBA) was used to quickly assess the whole-body posture load. Results The PLIBEL assessment results showed that various adverse ergonomic factors affected different parts of the body during the work process of medical staff. Specifically, 18 adverse ergonomic factors were identified in the neck, shoulders, and upper back, while 10 adverse ergonomic factors were identified in the elbow, forearm, hand, and lower back. Rehabilitation therapists and nurses engaged in patient handling in general wards and medication preparation and blood collection were exposed to ≥35 adverse ergonomic factors. The REBA assessment showed that the REBA score was 3-12 points for medical staff during their work process. Rehabilitation therapists were classified as having an extremely high ergonomic risk. High-risk occupations included ward housekeeping nurses, surgery assistant nurses, operating-room instrument nurses, and surgeons. Medium-risk occupations included general ward nurses (medication preparation and blood collection, venipuncture/infusion, and patient handling), intensive care unit (ICU) nurses, internal medicine residents, and dentists. Low-risk occupations included administrative front-desk nurses, outpatient internal medicine physicians, and technicians/physicians in ultrasonography, laboratory medicine, physical examination, and occupational health departments. Conclusion Adverse ergonomic factors of medical staff predominantly affect the neck, shoulders, upper back, elbows, forearms, hands, and the lower back during the work process. Rehabilitation therapists, ward housekeeping nurses, ICU nurses, operating-room instrument nurses, and surgeons are high-risk groups for WMSDs. Attention should be paid to the management and control of adverse ergonomic factors for medical staff to prevent the occurrence of WMSDs.