The invention discloses a lignosulfonate alkylation modified surfactant and a preparation method and application thereof. The method comprises the following steps of: dissolving lignosulfonate in a mixed solution of an organic solvent and water, regulating the pH value of the solution to 10 to 12, and stirring to ensure that the lignosulfonate is dissolved fully; and adding halogenated hydrocarbon and an alkaline organic amine catalyst, performing reflux reaction under the protection of inert gas, cooling, performing acid precipitation on a reaction solution, washing and drying to obtain the lignosulfonate alkylation modified surfactant. According to the lignosulfonate alkylation modified surfactant, the alkaline organic amine catalyst is used, and the mixed solution of the organic solvent and the water is used as a reaction solvent, so that the problems of a non-ideal effect of heterogeneous reaction and low activity of modified products, which are caused by difference of the oleophylic and hydrophilic performance of the lignosulfonate and an alkylation reagent, are solved, and the obtained lignosulfonate alkylation modified surfactant of which the surface tension is 29.299mN/m meets the activity requirement of daily washing. According to the method, one-step reaction is adopted, and the yield is 91 percent, so the method is good in industrial prospect.