Provided are an antibody that binds to the PD-L1 protein or CD137 protein, an antigen-binding fragment or a variant thereof, as well as a bispecific antibody that can bind to both the PD-L1 protein and the CD137 protein. The bispecific antibody has a strong ability to specifically recognize the PD-L1 protein and the CD137 protein, and can enhance T-cell activity. Also provided is the use of the antibody or the antigen-binding fragment or the variant thereof and the bispecific antibody in the prevention and treatment of tumors.
