The invention discloses a single-component water-based epoxy resin emulsion, which comprises the following components in percentage by weight: 100 percent of a modified epoxy resin, 5-35 percent of an efficient emulsifier, 0-1 percent of a surfactant, 0-70 percent of a cosolvent and an appropriate amount of water, wherein the modified epoxy resin comprises an epoxy resin, polyglycol ether, isocyanate, a sealing agent and a catalyst; the efficient emulsifier consists of an epoxy resin, polyether, organic silicon and a catalyst; the surfactant is one or a mixture of more than two of sodium dodecylbenzene sulfonate, sodium lauryl sulfate and potassium dodecyl sulfate; the cosolvent is one or a mixture of more than two of propylene glycol methyl ether, glycol ethylene ether, ethylene glycol monomethyl ether and diacetone; the sealing agent is one or a mixture of more than two of caprolactam, phenol and methyl ethyl ketoxime; and the catalyst is one or a mixture of more than two of 2-ethyl-4-methylimidazole, triphenylphosphine, triphenylhydrogen phosphide or benzyl dimethylamine.