The invention belongs to the technical field of epoxy resin curing agents, and discloses a cardanol modified amine epoxy resin curing agent as well as a preparation method and application thereof. Thecuring agent is prepared by the following steps: mixing cardanol and phenols, heating to 30-40 DEG C, stirring, adding alkali, heating to 60-70 DEG C, adding an acid catalyst, stirring to dissolve, heating to 80-90 DEG C, reacting, standing, separating liquid, and vacuumizing to obtain an intermediate product; and heating the intermediate product to 30-40 DEG C, stirring, adding aldehyde, controlling the temperature to be less than 50 DEG C, dropwise adding amine at 30-40 DEG C after the aldehyde is added, stirring, heating to 115-175 DEG C, cooling to 90-95 DEG C after the reaction is finished, and carrying out vacuum dehydration under reduced pressure. The curing agent has good hydrophobicity, flexibility and protective function, mild heat release and moderate curing speed, avoids degradation of the toughness of epoxy resin in the fast curing process, and is applied to the field of quick curing or toughening of epoxy resin.