The invention discloses preparation methods and use of an indole alkaloid compound. The invention produces a structural-novel indole alkaloid compound by using Penicillium crustosum PRB-2 collected from the deep ocean of Prydz Bay, Antarctica or a chemical synthesis method. The indole alkaloid of the present invention showed good anti-influenza A virus activity both in vitro and in vivo activity tests, and can be used as a new antiviral drug in the form of naristillae, nasal spray or oral preparation for the prevention and treatment of influenza A virus infection.