The present invention provides an siRNA for inhibiting apolipoprotein C3 (ApoC3) gene expression, and a pharmaceutical composition and conjugate containing the siRNA. Each nucleotide in the siRNA is a modified nucleotide. The siRNA contains a sense strand and an antisense strand； the sense strand contains a nucleotide sequence A, the nucleotide sequence A having a length that is equal to that of a nucleotide sequence represented by SEQ ID NO:1 and having no more than three nucleotide differences； the antisense strand contains a nucleotide sequence B, the nucleotide sequence B having a length that is equal to that a nucleotide sequence represented by SEQ ID NO:2 and having no more than three nucleotide differences. The siRNA and the pharmaceutical composition and conjugate thereof provided in the present invention can effectively treat and/or prevent dyslipidemia.本發明提供一種抑制載脂蛋白C3(ApoC3)基因表現的siRNA，含有該siRNA的藥物組合物和綴合物。該siRNA中的每個核苷酸均為修飾的核苷酸，該siRNA含有正義鏈和反義鏈，該正義鏈含有核苷酸序列A，該核苷酸序列A與SEQ ID NO：1所示的核苷酸序列長度相等，且不多於3個核苷酸差異，該反義鏈含有核苷酸序列B，該核苷酸序列B與SEQ ID NO：2所示的核苷酸序列長度相等，且不多於3個核苷酸差異。本發明提供的siRNA及其藥物組合物和綴合物，可以有效治療和/或預防血脂異常。
