A large number of natural gas vehicles(NGV) with composite cylinders run in the world. In order to store hydrogen, using the composite cylinder has also reached commercialization for the hydrogen fuel cell vehicle (FCV) which is been developing on ECO Energy. Under these increasing circumstances, the most important issue is that makes sure of safety of the hydrogen composite cylinder. In case of the composite cylinder, a standards to verify the safety of cylinders obey several country's standards. For NGV, ISO 11439 has adopted as international standards, but for FCV, it has been still developing and there is only ISO/TS 15869 as international technical standards. In contents of international standards, the fire test is the weakest part. The fire test is that the pressure relief valves (PRD) normally operate or not in order to prevent cylinders bursting when a vehicle is covered by fire. However, with present standards, there is no method to check the problem from vehicles in local flame. This study includes fire test results that have been performed to establish the fire-test standards.