The invention discloses Karbofos emulsion in water, which comprises the following components in percentage by weight: 20 percent to 70 percent of karbofos active compound, 0 to 15 percent of organic solvent, 2 percent to 15 percent of emulsifying agent, 0.5 percent to 5 percent of antifreeze, 0 to 3 percent of thickening agent and the rest of water; the organic solvent is toluene, dimethylbenzene, benzene or C10 aromatic hydrocarbon, the thickening agent is aluminium-magnesium silicate, organobentonite, xanthan gum or carboxymethyl cellulose, the antifreeze is glycol, propanetriol, isopropanol or butanol, and a stabilizing agent is antioxidant 264, epoxy chloropropane, epoxidized soybean oil or benzoperoxide, the emulsifying agent is calcium dodecyl benzene sulfonate or K-12, alkyl naphthalene sulfonate, nonyl phenol polyoxyethylene ether, alkylaryl polyoxyethylene ether, polyoxyethylene fatty acid, PO-EO block polyether, polycarboxylate, polyoxyethylene hydrogenated castor oil and styryl phosphate. The emulsifying agent is more likely to be one or several of PO-EO block polyether, alkyl naphthalene sulfonate, nonyl phenyl polyoxyethylene ether, alkylaryl polyoxyetheylene ether, polyoxyethylene fatty acid and styryl phosphate mixed in any proportion. The Karbofos emulsion in water is a high-efficient, safe, economical, convenient and environment-friendly farm chemical.