The ethanol aqueous solution possesses an extensive application in energy and chemical industry, however, it easily catches fire owing to its high-volatile and flammable property. In current research, the combustion behavior and oscillatory regime of flame spread over ethanol aqueous solutions with different proportions are investigated and characterized. The measured velocity and the size of subsurface flow prove that the amount of thermal exchange energy is enhanced by the addition of water in the solution. Moreover, a flashpoint prediction model is developed based upon the equation of Clausius-Clapeyron, the Raoult's law and the ideal solution theory. The scaling analysis identifies that the reciprocal flashpoint is directly proportional to the molar ratio of ethanol. Furthermore, three oscillatory regimes are observed with different proportions of ethanol: the "continuous advancement" regime, the "forward-reverse-forward" regime and the "forward-stagnation-forward" regime. Thus, the proportioning ethanol aqueous solutions can be used to simulate the flame spread behaviors of various flammable liquids. This finding possesses a potential significant guiding on the rapid analysis of the scene of oil spilling accident.