Abstract: The charge performance of ash generated from co-combustion of different types of coals and biomass fuel (corn stalk) was studied using faraday-cup detector and electrical low pressure impactor (ELPI). The results show that the charge capacity of co-combustion ash rises a little with the increase of biomass in fuel mixture. The reason is that different types of co-combustion ash have different chemical compositions and structural features. This improves the relative dielectric constant, specific resistance and surface adsorptive ability, and thus promotes the charge performance of co-combustion ash. Although the addition of biomass in fuel mixture raises the charge capacity of co-combustion ash, particle size is still the main influence factor on its charge performance.