19%以上。In order to investigate the heat exchange principle between the ceramic balls heat carrier and biomass powder, heat exchange experiments were conducted with ceramic balls of 90℃ at 1.0, 1.2 and 1.4kg/min and biomass powder of ambient temperature in a vertical down tube heat transfer reactor. The percentages of heat conduction and heat convection of the total endothermic flux of the biomass powder were determined at different ceramic balls mass flow by heat balance analytic method. The results indicate that the heat conduction was the dominant heat transfer mechanism which reached 61%～87% during the heat exchange between the solid heat carrier and biomass powder. The heat conduction ratio decreased distinctly and the heat convection increased over 19% when the ceramic balls mass flow increased from 1.0kg/min to 1.4kg/min. 