Nowadays, the hospital emergency department admits critically ill patients from pre-hospital emergency or other medical center, and it undertakes the duty of recording the patient's vital signs to enter the clinical departments, special departments, and operating room of same hospital and other hospitals. Emergency nurses’ behavior with critically ill patients can have positive and negative impact on them that identifying and describing of these states require the experiences of nurses in this department, resulting in promotion and development of nursing knowledge in the emergency department. Therefore, this study was conducted to examine the experiences of emergency nurses in dealing with of critically ill patients. In this study, descriptive phenomenology method was used. Data were collected through 6 unstructured interviews with emergency nurses and colaizzi method was used to analyze the data. Results: three of participants were male, and three of them were female who had 7 to 15 years of experience of working in the emergency department. Nineteen codes of level 2, 9 codes of level 3 and finally 4 themes were extracted from data. Based on these themes and codes, the experiences of nurses in terms of care of critically ill patients were explained. These themes include the outcome of patients, tears and smiles, teamwork, and challenges. The findings of this study can assist nurses and nursing managers in further understanding of experiences of nurses in the care of critically ill patients, better understanding of issues faced by nurses, and improving the performance of nurses.