Abstract: In order to study the influence of different fuel mixture and fuel leakage rate on the spreading characteristics of spill fire, this paper conducts research on the combustion characteristics of n-butanol-ethanol mixed fuel spill fire with different mixing ratios and leakage rates based on a spill with dimensions of 100 cm×4 cm. The results show that during the forward process, the spreading pattern of the mixed fuel spill fire flame changes with the increase of the fuel leakage rate, dividing into three modes, "jump-recoil-crawl", "jump-crawl", and "uniform spreading", and there will be no "recoil" phenomenon as the mixing ratio increases; for the same leakage rate of the mixed fuel, the flame height decreases as the n-butanol-ethanol mixing ratio increases; the spreading velocity of the mixed fuel spill fire after adding ethanol to n-butanol increases, and the average spreading speed increases by 46.55% when the mixing ratio rises from 10：0 to 10：4; under the same leakage rate conditions the temperature and radiant heat flux density in the spill fire area decrease as the n-butanol-ethanol mixing ratio increases.

Key words: spill fire, n-butanol, ethanol, mixed fuel, spread characteristics