Disclosed are an anti-CD20-Flex bifunctional fusion protein, and preparation method and use thereof in the preparation of antitumor drugs. More particularly, disclosed are a bifunctional fusion protein CD20-Flex having a complete-antibody-like structure and function, and amino acid sequence, preparation method and use thereof in the preparation of the antitumor drugs. The bifunctional fusion protein CD20-Flex is able to combine with CD20 and also has the function of Flt3 ligand, thus effectively stimulating the tumor specificity immunity of the body while having lethality.
