The invention discloses a preparation method of a phenolated lignin amine cationic emulsifier. The method comprises the following steps: heating an alkaline liquid of alkali lignin and a proper amount of phenol to 70-100 DEG C and reacting for 1-3h, then, acidizing a reaction liquid to realize pH=2.5 with 1 mol/L hydrochloric acid, performing suction filtration, washing with hot water at 80-100 DEG C until free phenol disappears completely, thus obtaining phenolated lignin; dissolving the phenolated lignin in a NaOH liquid with mass fraction of 10% and regulating pH to 10.5-12, then, further adding a mixed liquid of a certain amount of small molecule polyamine and 37% formaldehyde, reacting for 3-5h at 90 DEG C, then, introducing amine methyl hydrophilic groups into the phenolated lignin, thereby obtaining the cationic emulsifier which has positive electricity under the condition of diluted acid. In comparison with the cationic emulsifier modified by the lignin which is not phenolated, the emulsifier provided by the invention has higher surface activity, stronger Zeta potential and stronger emulsion stability, and can be widely used in the fields of road engineering, building waterproofing, material corrosion prevention, water conservancy construction, and so on.