Provided are an siRNA for inhibiting expression of a Hepatitis B virus gene, and a pharmaceutical composition and conjugate containing the siRNA. Each nucleotide in the siRNA is an independently modified or unmodified nucleotide； the siRNA comprises a sense strand and an antisense strand； the sense strand comprises a nucleotide sequence A； the length of the nucleotide sequence A is the same as that of a nucleotide sequence as shown in SEQ ID NO: 1, and the number of the nucleotide differences is not more than three； the antisense strand comprises a nucleotide sequence B； and the length of the nucleotide sequence B is the same as that of a nucleotide sequence as shown in SEQ ID NO: 2, and number of nucleotide differences is not more than three.
