The Emergency Department (ED) plays an important role in the healthcare field, due to the nature of the services it provides, especially for patients with urgent cases. Therefore, good management of ED is very important in improving the quality of services. Good management depends on the effective use of material and human resources. One of the most common problems that the ED suffers from is the long waiting period and the length of the patient’s stay. Many researchers have proposed many solutions to reduce waiting time and length of stay (LOS). One of the best solutions for resource optimization is modeling and simulation based on inputs such as patient length of stay and door-to-doctor time (DTDT). In this study, the ED was modeled using a Coloured Petri Net, and to determine the number of resources needed, genetic algorithms were used. This study was conducted in the ED of Hassani Abdelkader Hospital in Sidi Bel Abbes, and several simulation models were evaluated, which reduced the waiting time and the length of stay for the patient.