Pyrolisis of biomass result in smoke that can be condensed to be liquid smoke. Liquid smoke is a brown mixture， which contains phenols， aldehydes， ketones， acids， esters， etc. The flavor and color of liquid smoke can endow food with unique quality. Liquid smoke's basic ingredients are phenols， carbonyl compounds and organic acids， which have the function of antibacterial， anti-corrosion， anti-oxidation. The food of fluid smoking has unique flavor and can prolong their shelf life of products， so liquid smoke can be used in livestock products and aquatic products. The review summarizes the recent research progress in the main components， formation process， and application in food of liquid smoke. According to the characteristics of smoked food， the review can provide reference and basis for the development of compound liquid smoke with high color， flavor， antibacterial and antioxidant properties.