Fibrous filter cartridges are commonly used to separate the liquid droplets from aerosols. As the droplets are captured and coalesce in the filter layers, the pressure drop across the filter increases dramatically. Liquid saturation and distribution in the filter cartridge have a significant influence on the pressure drop, which has rarely been previously investigated. The study reported in this paper describes the distribution characteristics of the liquid in the filter layers and inside and outside of the filter cartridge during the gas liquid filtration process. To obtain the vertical distribution of the liquid saturation, the filter cartridge was divided into three sections and the cylindrical filter elements (termed filter-plugs) were fixed inside the filter layers at various heights. A vertical aerosol sampling device was installed in the filter to determine the aerosol concentration inside and outside of the filter cartridge. The experimental results showed that non-uniform liquid distribution characteristics existed at various heights in the filter cartridge during the different stages of the filtration process. The outlet concentration increased from the top to the bottom of the filter cartridge, which corresponded to the various stages of gas-liquid filtration process. In addition, the distributions of the vertical aerosol concentration inside and outside the filter cartridge were different due to the gas flow direction and the tubular structure of the filter cartridge. (C) 2016 Published by Elsevier B.V.