An antibody-drug conjugate, a pharmaceutically acceptable salt thereof, a solvate thereof, or a solvate of the pharmaceutically acceptable salt thereof, wherein the antibody-drug conjugate has a structure shown in formula I; wherein Ab is a B7-H3 antibody or a variant of the B7-H3 antibody; m is 2 to 8; the amino acid sequence of the light chain in the B7-H3 antibody is shown in SEQ ID NO: 1, and the amino acid sequence of the heavy chain is shown in SEQ ID NO: 2; the variant of the B7-H3 antibody is at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical to the B7-H3 antibody; D is a cytotoxic drug topoisomerase inhibitor, wherein the cytotoxic drug topoisomerase inhibitor is R 2 and R 5 are each independently H, C 1 -C 6 alkyl, or halogen; R 3 and R 6 are each independently H, C 1 -C 6 alkyl, or halogen; R 4 and R 7 are each independently C 1 -C 6 alkyl; R 1 is C 1 -C 6 alkyl substituted by one or more than one -NR 1-1 R 1-2 , C 1 -C 6 alkyl substituted by one or more than one R 1-3 S(O) 2 -, C 1 -C 6 alkyl, C 3 -C 10 cycloalkyl, C 6 -C 14 aryl, or 5- to 14-membered heteroaryl; the heteroatom in the 5- to 14-membered heteroaryl is selected from one or more than one of N, O, and S, and the number of heteroatoms is 1, 2, 3, or 4; the R 1-1 , R 1-2 , and R 1-3 are each independently C 1 -C 6 alkyl; L 1 is independently one or more than one of a phenylalanine residue, alanine residue, glycine residue, glutamic acid residue, aspartic acid residue, cysteine residue, histidine residue, isoleucine residue, leucine residue, lysine residue, methionine residue, proline residue, serine residue, threonine residue, tryptophan residue, tyrosine residue, and valine residue; p is 2 to 4; L 2 is or wherein n is independently 1 to 12, the c-terminal is connected to L 1 through a carbonyl group, and the f-terminal is connected to the d-terminal of L 3 ; L 3 is wherein the b-terminal is connected to the Ab, and the d-terminal is connected to the f-terminal of L 2 . wherein Ab is a B7-H3 antibody or a variant of the B7-H3 antibody; m is 2 to 8; the amino acid sequence of the light chain in the B7-H3 antibody is shown in SEQ ID NO: 1, and the amino acid sequence of the heavy chain is shown in SEQ ID NO: 2; the variant of the B7-H3 antibody is at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identical to the B7-H3 antibody; D is a cytotoxic drug topoisomerase inhibitor, wherein the cytotoxic drug topoisomerase inhibitor is R 2 and R 5 are each independently H, C 1 -C 6 alkyl, or halogen; R 3 and R 6 are each independently H, C 1 -C 6 alkyl, or halogen; R 4 and R 7 are each independently C 1 -C 6 alkyl; R 1 is C 1 -C 6 alkyl substituted by one or more than one -NR 1-1 R 1-2 , C 1 -C 6 alkyl substituted by one or more than one R 1-3 S(O) 2 -, C 1 -C 6 alkyl, C 3 -C 10 cycloalkyl, C 6 -C 14 aryl, or 5- to 14-membered heteroaryl; the heteroatom in the 5- to 14-membered heteroaryl is selected from one or more than one of N, O, and S, and the number of heteroatoms is 1, 2, 3, or 4; the R 1-1 , R 1-2 , and R 1-3 are each independently C 1 -C 6 alkyl; L 1 is independently one or more than one of a phenylalanine residue, alanine residue, glycine residue, glutamic acid residue, aspartic acid residue, cysteine residue, histidine residue, isoleucine residue, leucine residue, lysine residue, methionine residue, proline residue, serine residue, threonine residue, tryptophan residue, tyrosine residue, and valine residue; p is 2 to 4; L 2 is or wherein n is independently 1 to 12, the c-terminal is connected to L 1 through a carbonyl group, and the f-terminal is connected to the d-terminal of L 3 ; L 3 is wherein the b-terminal is connected to the Ab, and the d-terminal is connected to the f-terminal of L 2 . <EOS>