The High quality cardiopulmonary resuscitation (CPR), defibrillation, and drug administration have influence on the return of spontaneous circulation (ROSC) in cardiac arrest victim. In out-of-hospital environment, the influencing factors of quality of CPR include manpower, fatigue of the rescuers, space limitation of the ambulance, chest compression and ventilation within moving ambulance, CPR experience of the emergency medical technicians, and transport distance. The purpose of the study is to investigate the ventilation and chest compression within moving ambulance. The subjects were 763 firefighters in Gyeonggido. Male accounted for 87.8%. Emergency medical technician 1 (EMT-1) was 29.9%. and EMT-2 was 70.1%. One handed chest compression accounted for 14.0% and two handed chest compression accounted for 86.0%. Chest compression only accounted for 71.3% and the compression to ventilation ratio of 30:2 was performed in 28.7%. EMT-1 was more skillful than EMT-2, but there was no statistical significance between the compression to ventilation ratio of 30:2 CPR, chest compression only, one handed compression and two handed compression.