Abstract: The change rule of the auto-ignition points of anhydrous ethanol, methanol, n-butanol, n-propanol, isopropanol, ethyl acetate and binary mixed liquids with different proportions were studied. The results show that the auto-ignition point will decrease with the increase of the low auto-ignition point liquid for these binary mixed flammable liquids. However, for the mixed solution of ethyl acetate and methanol that reacts at high temperature, its auto-ignition point does not conform to this law. When the auto-ignition points of the two components of the binary mixed liquid have a large difference, the auto-ignition point of the mixed liquid is between the two pure solutions. When the auto-ignition points of the two components are large and the difference is small, the auto-ignition point is lower than the auti-ignition point of the pure solutions of the two.When there is an isomer in the solute of mixed solution, the spontaneous combustion point of mixed solution will change suddenly.