Abstract: Aiming at the present situation regarding the handling of the coarse banana straws which are labor intensive, high water content, and unavailability of satisfactory straw solid molding equipment in the tropical agricultural areas of China, the biomass pellet densifying machine for banana stem was designed. The main structural parameters of screw extrusion device, mixing device, extrusion device and draining mechanism were determined. The results of machine performance test showed that the productivity was 358 kg/h, forming rate of particle fuel was 95.4%, mechanical durability was 96.7%, particle density was 1.35 g/cm3, and particle moisture content was 2.76%. The machine can meet the requirements of biomass pellet fuel forming, which has durable, stable and reliable performance, as while as obvious economical and ecological benefit. It will have the broad prospect of application in the tropical agricultural areas in China.