The explosion limits and the least suppression explosion concentrations of RP-5 oil,RP-3 oil and alcohol air mixtures were measured respectively by use of the apparatus,which was designed for measuring explosion limit of combustible liquid vapor. Results indicate the explosion limits of RP-5 oil,RP-3 oil and alcohol air mixtures are 1.53%~7.73% (vol.), 0.82%~7.17% (vol.) and 3.38%~18.25% (vol.) respectively; the least suppression explosion concentrations of the 1301 inert gas are 6.75%,6.8% and 5.56% respectively for the RP-5 oil,RP-3 oil and alcohol air mixtures. The least suppression explosion concentrations of N2 and CO2 are 49% and 45% respectively for the RP-3 oil air mixtures. So the suppression effect of the 1301 inert gas is better than that of the CO2 and the N2