Abstract: 【OBJECTIVE】To explore bio-activity of polysaccharide from Coprinus comatus, antiviral activity of polysaccharide from Coprinus comatus on tobacco mosaic virus (TMV) was investigated. It can provide theoretical evidence for purification. 【METHOD】Polysaccharide of fruiting body and polysaccharide of mycelium were isolated from Coprinus comatus, and their antiviral activity were researched. 【RESULTS】 Polysaccharide from Coprinus comatus had strong antiviral activity of preventing infection of virus, affected significantly multiplication of TMV and can reduce infection when applied before TMV inoculation. 【CONCLUSION】Polysaccharide from Coprinus comatus had strong antiviral activity.