The invention discloses an adhesive based on corn ears and a preparation method thereof. the adhesive comprises the following raw materials in parts by weight: 70 to 80 parts of modified expanded cornmeal, 10 to 20 parts of softened and modified corncob meal, 5 to 10 parts of softened and modified corn peel powder and 5 to 10 parts of kaolin powder. The cheap corn ears capable of being easily obtained are used as raw materials for preparing the adhesive through a series of preparation processes; the preparation process is simple; green and environment-friendly effects are achieved; the popularization is easy; the prepared adhesive has the advantages of great size and light specific weight; the addition is smaller than that of wheat flour; the raw material cost is directly reduced. The adhesive solves the problems that the wheat flour is added into the adhesive in order to increase the solid content and the viscosity value, but the food of people is reduced; artificially made plate enterprises use wheat flour, causing high cost. Through the natural baking fragrance of the modified puffing corn powder, the environment pollution defect of formaldehyde smell of the adhesive is overcome, so that the adhesive using the technical scheme disclosed by the invention has great market application and popularization values.