The invention provides an amine emulsifier. The structural formula of the amine emulsifier is as shown in the specification, wherein R1 represents one of tetradecyl, hexadecyl, octadecyl, oil base and rosinyl; R2, R3 and R4 all represent ethyoxyl; or R2, R3 and R4 all represent methyoxyl; or R2, R3 and R4 all represent methyl; or R2 represents methyl, and R3 and R4 both represent methyoxyl; or R2 represents methyl, and R3 and R4 both represent ethyoxyl. The amine emulsifier is capable of reducing the viscosity of an asphalt-recycling agent and guaranteeing that the asphalt-recycling agent has good fluidity both at normal temperature and low temperature in winter to facilitate construction. The invention also provides a preparation method of the amine emulsifier and the application of the amine emulsifier in producing an emulsified asphalt-recycling agent; the emulsified asphalt-recycling agent is used for preparing an asphalt mixture, so that the water damage resistance of a pavement can be remarkably improved on the premise of ensuring no reduction in the low-temperature anti-crack property and anti-fatigue property of the pavement.