The most important function of an emergency medical service (EMS) information system is to enhance the overall quality of emergency medical services with information technology, cooperated with professional skill of Emergency Medical Technician (EMT), and thereby reduce the pain and incidence of death among emergency patients. According to the statistics, the average travel time for an ambulance to commute from the accident location to the emergency room of a hospital is about ten minutes in cities and around 40 minutes in remote areas. Currently, EMTs strive to maintain the vital signs of patients during this time and document the patient's demographic data, vital signs, reasons for needing emergency aid and during the same time, the hospitals should be informed of the patients' conditions. If we using an EMS information system to assist EMTs in those processes of above, so EMTs can fill out the data sheet more conveniently, then the EMTs can use the extra time to better serve the medical needs for the patient. The purpose of this study was to evaluate the effectiveness of an emergency medical service information system for mobile devices. In addition, the study examined the process of connecting electronic equipment such as an IC card reader and an electronic sphygmomanometer as aides in helping the EMT gather data and judge the patient's condition in order to offer more appropriate care. The generated data sheet was then transformed into TMT (Taiwan Electronic Medical Record Template) format as set up by this study. This data format can also be automatically converted into the hospital information system format in order to avoid previously redundant standard paper work. The study's questionnaire was responded to by EMTs who had used the information system in field practice. Compared to the traditional paper work, the results of the t-test analysis showed a significantly higher level of satisfaction among those EMTs who used the information system. The study provided evidence that the system could be really helpful to EMT.