Abstract: Main accident types of car-mounted CNG cylinder are introduced and accident causes of car-mounted CNG cylinder are analyzed. The author presents safety countermeasures against risk of car-mounted CNG cylinder and solutions to the accident and/or emergency response from the quality standards of CNG and installation method of CNG. It is pointed out that sound standards on CNG cylinder should be established and CNG cylinder manufacturing code with different materials, regular inspection and safety evaluation standard should be implemented.