Method for preparing Cemdisiran

The invention provides a method for preparing Cemdisiran (Cemdisiran). Wherein the Cemdisiran is siRNA (small interfering Ribonucleic Acid) and is formed by complementarily pairing a positive-sense strand and an antisense strand; the preparation method comprises the following steps: mixing a positive-sense strand substrate, an antisense strand substrate and RNA ligase, and catalyzing the positive-sense strand substrate and the antisense strand substrate to be connected through a phosphodiester bond by utilizing the RNA ligase to obtain a positive-sense strand and an antisense strand so as to obtain Cemdisiran; the positive-sense strand substrate can form a positive-sense strand, and the antisense strand substrate can form an antisense strand. Compared with Cemdisiran prepared through chemical synthesis, the product obtained through the preparation method is high in purity and few in impurity, the reaction condition is mild, and industrial large-scale production can be achieved conveniently. 本发明提供了一种制备Cemdisir