The present invention discloses an additive for preventing a potassium fertilizer from powder generation, and an application method thereof, and belongs to the technical field of fertilizers. The additive comprises, by weight, 0.5-10 parts of a urea-formaldehyde resin, 0.2-15 parts of water, and 0.05-1.5 parts of talc powder. According to the present invention, based on the particle extrusion, the urea-formaldehyde water-soluble material is coated on the extruded particle surface to form the film on the particle surface, such that the effects of damage resistance, moisture resistance, and powder generation prevention are provided; and the additive has characteristics of low cost, simple process, easy operation, strong expansion, safety, and environmental protection.