Abstract: An application of HJT aqueous extract in the preparation of drugs against a Blue-ear disease is provided. For the first time, it is found in the present invention that HJT extract has a significant effect of preventing and treating the Blue-ear disease. Specifically, through experiments of qRT-PCR and immunofluorescence techniques, the present invention has proved that HJT extract can significantly inhibit infection and replication of PPRSV with significant antiviral effect, so that it is expected to become a new type of biologically active substance for prevention and treatment of Blue-ear disease. The product prepared by the method can be used as natural antiviral drugs for the prevention and treatment of the Blue-ear disease, realizes the comprehensive utilization of HJT plants, and improves its value, which has a good application prospect.