Flammable liquids are widely used in food, chemical industry, energy, and other fields, and have created great economic value. However, these liquids are flammable and explosive and sometimes generate toxic vapor, and thus their nondestructive detection is of great importance for promoting industrial production and guaranteeing personal and property safety. Spectroscopic methodologies have the advantages of fast response, online and nondestructive detection, no need of sample pretreatment, and high precision, playing an important role in the detection of flammable liquids. In this paper, we expounded the technical principles of the spectroscopic methodologies for flammable liquids and highlighted the development history and application status of five typical spectroscopic methodologies for flammable liquids, including near-infrared spectrometry, Raman spectrometry, ultraviolet-visible spectrophotometry, fluorescence spectrometry, and terahertz time-domain spectroscopy. Furthermore, we discussed the future potential applications of these spectroscopic methodologies in combination with their advantages and disadvantages.