Abstract: In order to effectively solve the problems of drying biomass powder which was used for compression molding technology, a double-tube structure was used to extend the residence time and drying processes of the biomass powder in the high temperature tube. The sizes and the parameters of the main parts of the drier (the drying pipe) were designed and calculated respectively. The suitable models were selected, and the ancillary equipment of the drier (the cyclone, the fan and the stove) were selected as well. Finally, corn straw powder was taken as the testing object to carry out the experiments on heat balance and material balance on the prototype of this drier. The results showed that the main thermal performance parameters, such as the total heat input and output, the volume of water evaporation and the humidity of materials all met the design requirements. The humidity of dried material could reach 8%-12%, and the drying efficiency could be up to 28.1% as well. All these indices coincided with the national standards of driers, and the double-tube airflow drier was especially suitable for drying the biomass powder which was used for compression molding technology.