Abstract: The higher fatty amine/formaldehyde modified lignin quaternary ammonium salts (KL-F-HFA-QASs) cationic asphalt emulsifiers were made by the Mannich reaction and O-alkylation reaction.The effects of some factors on the Mannich reaction were discussed.The experiments showed that the Mannich reaction in dioxane aqueous solution could improve the reaction efficiency obviously.Reaction temperature was 60℃.With increasing octadecylamine dosage, the amount of nitrogen in the modified lignin amines increased.The nitrogen content of modified lignin amines reached a maximum when the molar ratio of formaldehyde to octadecylamine was 1.5∶1.The measurements of physico-chemical properties showed that among different KL-F-HFA-QASs dodecylamine-formaldehyde modified lignin quaternary ammonium salt (KLQAS)solution had the highest surface activity,and smaller surface tension of 33.2 mN•m^-1 that was much lower than 43.8 mN•m^-1 of KLQAS.The emulsifying capacitiy of KL-F-HFA-QASs was improved obviously.Zeta potential of asphalt particles made from dodecylamine-formaldehyde modified KLQASs inceased more rapidly than that of KLQAS.