An immunosensor for the sensitive and simple recognition of low concentrations of influenza viruses was constructed.Gold electrode was coated with H1 subtype-specific monoclonal antibodies to selectively capture the target virus.Horseradish peroxidase（HRP） as a catalyst to reduce hydrogen peroxide（H2O2） in the methylene blue（MB） solution was immobilized on the biosensor.The change of reduction peak current for specific recognition of antigen virus was monitored by square wave voltammetry（SWV）.The biosensor exhibited a fast amperometric response and a good stability to H2O2-MB system.The dynamic range for antigen recognition was in the range of 0.01-2.0 μg/mL with a detection limit（S/N=3） of 5.0 ng/mL.The results indicated that HRP had a good sensitivity and a simple operation for the detection of influenza virus.