Objective: To investigate effects of different preparation processes on in vitro antiviral activity of Feiduqing prescription. Method: Antiviral activities of water extract(A)

water and alcohol extract(D)

water extraction-ethanol precipitation substance(B) and its n-butanol extract(C) were investigated by in vitro antiviral method. Result: Sample D could completely inhibit A 1 and 3 type influenza viruses with the concentration of 1 250 mg·L-1

sample A with 250 mg·L-1 could completely inhibit A 1 and 3 type influenza A viruses under 60% cytotoxicity

other samples had no inhibitory effect on other respiratory viruses

and in vitro antiviral activity of sample D was better than sample A. Conclusion: Different preparation processes of the same prescription had a certain influence of pesticide effect.