The invention belongs to the field of livestock medicines, and provides a long-chain non-encoding RNA (lncRNA) for inhibiting porcine reproductive and respiratory syndrome virus (PRRSV). The long-chain non-encoding RNA has a nucleotide sequence as shown in SEQ ID NO.1. A knock-down test proves that after the lncRNA disclosed by the invention in porcine alveolar macrophages is knocked down, the level of replication of the PRRSV is obviously increased relative to a control group without being knocked down; therefore, the lncRNA provided by the invention has an effect of inhibiting the replication of the PRRSV.