Various flammable vapors as energy source and raw material have been stored, transported in the indurstries, and accidental leakage of these vapors occurs occasionlly. Without an appropriate protection system, flammable vapors can be ignited and serious damage results from them. To reduce the risk cauesd by explosion, we should know the explosion limit and explosion characteristics. In this study, the maximum explosion pressure, the maximum explosion pressure rise, the effect of temperature and mixing with other vapor were measured in a cylindrical vessel. Experimental results showed that maximum explosion pressure of flammable vapor was about 3.1∼4.2 ㎏/㎠ and it was reached 3.4 times faster than that at explosion limit. The lower explosion limit was coincided well with Le Chateilier`s equation, however, upper explosion limit was not.