Abstract: Different test methods for determination of closed cup flash point of flammable liquid were described, and the different results of those methods for the determination of closed cup flash point of flammable liquids were compared and analyzed. The results show that when measuring the closed cup flash point of samples without film on the surface, testing the liquid samples to ASTM D6450-2016 is more suitable. It is recommended that viscous liquid samples are tested to ASTM D7094-2017a and paste samples are tested to ASTM D56-2016 or GB/T 21929-2008. For the samples with surface film, the methods with stirring function in the detection process are recommended. Commonly, the liquids or viscous liquid samples are tested to ASTM D7094-2017a and the paste samples are tested to ASTM D93-2016 or GB/T 261-2008.