Emergency department is considered as one of complex services in hospital. This complexity is due to: care process complexity, interference with other services, influx of patients, high constraints, etc. Problems observed in EDs are mainly due to the organization, constraints, and changes in the care missions, as well as the mismanagement of process flows (patients, information, resources, etc.). This context makes the emergency department to face strain situations. However, health staff are neither prepared nor trained to cope with such context. Therefore, they need decision support systems adapted to anticipate and manage such situations. This paper proposes a proactive reactive simulation-based control system named ED-CS to design a tool that ED managers can use as a decision-making tool for anticipating and managing of strain situations, as well as planning the strategic deployment of corrective actions when such strains situations occur. This paper focuses on the decision-making process and system functions to be developed to implement corrective actions needed to anticipate and manage these strain situations. A case study is used to illustrate and show the potential benefits of ED-CS to deal with strain situations.