The invention relates to the technical field of fire extinguishing agents, and discloses a water-based extinguishing agent, which is prepared from the following components in parts by weight 100 to 120 parts of deionized water, 5 to 10 parts of 
sodium lauroyl 
hydroxymethyl ethanesulfonate, 2 to 3 parts of 
lignin, 1 to 2 parts of a 
flame retardant, 20 to 30 parts of 
ethylene glycol, 0.3 to 0.8 partof a 
foaming agent, 0.3 to 0.6 part of a 
hydrocarbon surfactant, 0.3 to 0.6 part of a 
fluorocarbon surfactant, 0.3 to 0.4 part of a 
preservative and 0.4 to 0.5 part of an anti-
corrosion agent. The water-based extinguishing agent has the following advantages and effects that the 
sodium lauroyl 
hydroxymethyl ethanesulfonate, the surfactant and the water are mixed to obtain a solution with good foam performances, so 
heat transfer is effectively inhibited and 
oxygen is isolated, the compatibility of the 
lignin with the three-dimensional 
network structure and the 
sodium lauroyl 
hydroxymethyl ethanesulfonate polar group is improved through the interaction between the 
lignin and the sodium lauroyl hydroxymethyl ethanesulfonate polar group, the surface density of the foam is increased, and the foam is stable and not prone to breakage. By adding 
ethylene glycol and auxiliary reagents, the comprehensive performance of the water-based extinguishing agent is further improved, and the extinguishing agent with better fire extinguishing performances and a longer service life is obtained.