Abstract: The present invention discloses CLDN18.2-targeting antibodies, bispecific antibodies and use thereof The CLDN18.2-targeting antibody is a single-domain heavy-chain antibody that has high affinity for tumor cells endogenously expressing CLDN18.2 and can induce high endocytic activity. The bispecific antibody can target CLDN18.2 and CD3 and retains the binding effect of an Fc to an FcRn; meanwhile, a mutant Fc is preferred so as to reduce the binding to an FcgR and thus the activation of non-specific T cells caused by the cross-linking of an FcgR. The CD3-terminus activity is optimized so that the release of common cytokines in CRS, such as IL6 and TNF? can be reduced.