The invention discloses an adhesive for adhering automobile plastic parts and a preparation method thereof. The adhesive used for adhering automobile plastic parts comprises a component A and a component B in parts by weight, wherein the component A comprises epoxy resin, polyurethane modified epoxy resin, an epoxy diluent and a thixotropic agent in parts by weight; and the component B comprises the following raw materials in parts by weight: 10-40 parts of low molecular polyamide, 10-40 parts of alicyclic amine, a tertiary amine promoter and a coupling agent. The invention also discloses a preparation method of the adhesive for adhering automobile plastic parts, which comprises the steps of material taking, preparation of the component A and preparation of the component B. The adhesive provided by the invention has certain adhesive power to polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyamide (PA), polyvinyl chloride (PVC), polystyrene (PS), polycarbonate(PC), polyoxymethylene (POM), acrylonitrile-butadiene-styrene (ABS) and other materials, and the adhesive has good colloidal impact resistance, toughness and heat resistance, and can be used for adhering plastic parts at a high-temperature part such as an automobile engine.