Abstract: Abstract: A mass of Ramulus Mori (RM), Mushroom Planted Residual (MPR) are generated from sericulture and mushroom planting industries in China every year. After adequate drying and densification, these residues can be used as alternative raw materials of pellet fuel for heat generation. RM and MPR differ from crop stalks and sawdust for their physical characteristics and chemical composition. In order to produce high-quality pellet fuel from such materials，it is necessary to understand the role of these variations. The RM and MPR ( Main components: 85% Ramulus Mori, 12% cassava alcohol residues, 2% calcium oxide and 1% calcium sulfate) were tested for moisture content, net calorific value in air dried basis, contents of ash, volatile, fixed carbon, carbon, hydrogen, oxygen, nitrogen, sulphur and three biomass components (cellulose, hemicellulose and lignin). Also the glass transition temperature of two types of lignin which were extracted from RM and MPR, respectively, were determined by differential scanning calorimetry (DSC). The results showed that RM had low ash, sulfur and nitrogen content, but high volatile, net calorific value and glass transition temperature at 72.54%, 17.57 MJ/kg and 160℃, respectively, implying that RM was an excellent raw material for pellet fuel production, especially if the pressure and temperature during its pelletization can be controlled. The volatile, net calorific value and glass transition temperature of MPR were 66.72 %, 15.23 MJ/kg and 136.8℃, respectively, which were very significantly different from those of RM by univariate variance statistical analysis. Compared with RM, MPR had lower content of cellulose, hemicellulose and lignin. These results showed that the single MPR was not a suitable raw material for pellet fuel production, but an excellent briquetting binder. MPR was mixed with RM as a briquetting binder when the percentages of MPR content were 5%, 10%, 15%, 20%, respectively. The composites were grounded by vibrating screen (constant size at 4 mm) and conditioned at constant moisture contents (20%±0.5%). Then the pelletization tests were carried out by using a ring die pellet mill with different length-diameter ratio of ring dies. Therefore, the influence of the length-diameter ratio of ring dies and the mass ratio of RM/MPR on the pelletizing-molding ratio and some mechanical properties (density, durability, net calorific value, etc.) of RM/MPR composite pellets were analyzed. The result showed that the single RM cannot be densified effectively to produce durable pellets when length-diameter ratio of ring die was 4:1, and the pelletizing-molding ratio of single RM was low at 50.24%. One of the methods to increase the pelletizing-molding ratio was to increase the length-diameter ratio of ring dies. The pelletizing-molding ratio of single RM rose to 95.67% when the length-diameter ratio of ring die increased to 5.5:1, but working with such length-diameter ratio of ring die, the ring die pellet mill could be damaged easily. Another effective method to increase the pelletizing-molding ratio was to increase the mass proportion of MPR in the composites. During pelletizing process, MPR can be used as a briquetting binder to connect RM fibers due to its good performance of liquidity and cohesiveness. When mass proportion of MPR in the composites increased to 10% or 15%, the pelletizing-molding ratio of RM/MPR composite pellets was more than 91.54% with length-diameter ratio of ring die at 4:1. The density and durability of the RM/MPR composite pellets were enhanced when a small amount of MPR was added, which indicated that the mass proportion of MPR was proportional to density and durability of RM/MPR composite pellets. Meanwhile, RM/MPR composite pellets showed a satisfying value on net calorific value due to its volatility. When the mass proportion of MPR in the mixture was be within 0-20%, the density, durability and net calorific value of RM/MPR composite pellets was more than 1.208, 96.42% and 17.26 MJ/kg, respectively, which met the criteria of biomass pellet fuel.