Hospitals in Korea are enforcing a quality control over 119Emergency Medical Services to increase the survival rate of Out of Hospital Cardiac arrest patients. This study is to analyze the factors that effect the survival rate of Out of hospital Cardiac arrest patients by comparing the results of before and after the quality control enforcement. Cardiac arrest patients can be assorted into pre-decision group and decision group. The study analyzed the survival factors which was based on the adequate use of 119 BLS and ACLS usage rates, response time of 119EMS, qualification of ambulance worker, number of EMS team members, and adequate use of AED according to ECG diagnosis. The analyzation was done over total 1,233 of Cardiac arrest patients from January 1, 2010 to December 31, 2011 After the enforcement of the quality control, the usage of Vital sign check and BLS showed a big difference. Especially, as the usage of ECG showed a significant difference, Shockable rhythm, which is the most important to Cardiac arrest patients, also showed a significant difference. After the enforcement of quality control, the performance of ACLS showed a significant difference in IV. The study showed 119 ambulance workers provided better service in Vital sign and BLS and ACLS after the enforcement of quality control. It is considered a 119 ambulance service effects the survival rate of Cardiac arrest patients. Therefore, it can increase the survival rate and it is necessary to continue a quality control.