The COVID-19 pandemic presented substantial challenges to the healthcare systems in treating infected patients. The isolation ward is a crucial component in controlling the spread of respiratory diseases. A two-bed isolation ward is served as the subject of research, and the numerical simulation is used to analyze the indoor airflow distribution based on 12 cases with three ventilation modes and four patient relative postures. Three ventilation modes encompass stratum ventilation (SV), displacement ventilation (DV), and downward ventilation (DWV). Four patient relative postures involve supine (Sp-Sp), sitting (St-St), and side-lying in the same direction (Ly-Ly1) or back-to-back (Ly-Ly2). The results show that regarding the temperature distribution, and velocity distribution, air age distribution, DWV performs better than other ventilation modes. While regarding the contaminant concentration distribution, DV can better reduce the risk of cross-infection for patients and healthcare worker. This work can contribute valuable insights for the systematic design of wards in response to the emergent respiratory infectious diseases. It has significant practical implications for controlling the risk of cross-infection of respiratory diseases among personnel.