Infectious virus-laden aerosols generated during poultry processing may mediate airborne transmissions of avian influenza at live poultry markets. To develop effective control measures to reduce aerosol dispersion, we characterised the aerosol flow pattern of the mechanical defeatherers, a major source of aerosol dispersion during poultry processing at live poultry markets in China. Mechanical defeatherers create a strong air circulation during operation with inflow and outflow velocities over 1 m/s. A partial lid was designed to suppress the outflow and reduce aerosol dispersion. Computational fluid dynamics simulations confirmed that the partial lid prototype reduced the aerosol escape rate by over 65%. To validate the effectiveness of the partial lid in reducing aerosol dispersion, a field study was conducted at a retail poultry shop in Guangzhou and the concentrations of influenza viral RNA and avian 18S rRNA dispersed in air were monitored during poultry processing, with and without the use of the partial lid. At the breathing zone of the poultry worker, the use of the partial lid effectively suppressed the upward airflow and reduced the concentration of avian 18S rRNA in the air by 57%. The economic and practical partial lid can be easily implemented to reduce generation of influenza virus-laden aerosols at live poultry markets.