The invention discloses a collagen aggregate based flocculent antibacterial hemostatic material and a preparation method thereof. The preparation method is characterized by comprising steps as follows: DCMC (dialdehyde carboxymethyl cellulose) and silver nitrate are blended, a mixed solution containing nano-silver is prepared through redox reaction, then certain amount of collagen aggregate and certain amount of polyvinylpyrrolidone are dissolved in the mixed solution sequentially, the mixture is subjected to processes including gradient dilution, dealcoholization, vacuum drying, impregnation, freeze-drying, moderate grinding, sterilization and the like, and the collagen aggregate based flocculent antibacterial hemostatic material is obtained finally. The material adopts the collagen aggregate more similar to a natural tissue collagen structure, and compared with common collagen materials, the prepared flocculent hemostatic material has excellent physical and chemical properties and biological properties such as structural stability, mechanical property, biological degradability, biocompatibility and the like, can promote wound healing and repair, has broad-spectrum antibacterial/antimicrobial activity of the nano-silver, has large contact surface with the wound surface, is high in hydrophilia and stickiness and can be used for hemostasis repair of body surface wound and general civil hemostasis emergency.