The invention relates to a modified lauryl amine hardener and a manufacturing method and application of the modified lauryl amine hardener. The structural formula of the modified lauryl amine hardener is shown in the description. The manufacturing method of the modified lauryl amine hardener comprises the following steps: (1) adding lauryl amine and methyl isobutyl ketone (MIBK) in molar ratio of 1:1.2-2 in a four-opening flask with a stirring device, a thermometer and a water segregator; (2) stirring, leading counterflow of reaction to start to appear after heating temperature from common temperature to 71-75 DEG C, carrying over generated water by the MIBK with the performance of the reaction, achieving reaction end after gradually heating to 118-121 DEG C and reacting to that fact that water isn't generated any more; and (3) decreasing the temperature to 70-80 DEG C, obtaining excessive MIBK for recycle through reduced pressure distillation, and finally obtaining a modified lauryl amine hardener product. The modified lauryl amine hardener can be applied as a treating agent for solidification in the field of oil field sand prevention and can be manufactured to be a polyurethane waterproofing paint.