Emergency medical is an effective and efficient system that is used to minimize complications and casualties arising from emergency illness and events. Thus, Emergency Medical Services (EMS) system has been created in order to provide pre-hospital services. Its objective is quick responsive to treatment and keeping alive patients and finally if needed, patients are transferred to the hospital. System performance is affected by factors such as bases and ambulances' location, determine the number of required ambulance and allocation of them to the emergency calls. Therefore, location in order to maximize the populations that are covered and to provide favorable services to patients is one of major issues in EMS system. Facility location-allocation for EMS in order to effective decision making and programming appears in the two concepts. First, services' facility location and determine its capacity and secondly, allocation demand regions to the services facility. Current study focuses on covering model and hierarchical facility. This study used hierarchical maximal covering location-allocation problem with a combination of queuing theory to achieve the objectives of the research. HiQ-MCLP covering model is the developed model from MCLP that was created in order to maximize coverage and to increasing quality of services. A multi-objective mathematical model has been employed in the current study that minimizes costs and maximizes coverage. The model has been designed on two levels in order to location-allocation emergency vehicles such as ambulance in EMS and has been implemented in Boushehr. The model is solved in different confidence levels with Lingo15 software.