Abstract: With the social and economic development, demand of energy is increasing. Biomass pellet fuels have a wide range of renewable raw materials. Biomass pellet fuels with small storage space, easily transport and use of clean and green, high thermal efficiency, and sustainable use, have broad prospects for the development in the future. Long-term storage of biomass fuels is necessary because that there is a time gap between feedstock harvesting and production for at least 6 months of storage in the factory. In order to study whether they can be adapted to store under northern climate, the physical and chemical characteristics of the different storage methods (bagging, semi-closed, open-air), we carried out an experiment to study the laws of the three storage modes with corn pellets and wood pellets on March to August in 2011. The results showed that the all biomass pellet fuels did not appear mildew, while the changing laws of total water and bulk density were accordance with the climate changes. The range of the corn pellet fuels and wood pellet fuels in the open-air storage mode were the largest with (2.42% and 2.55% respectively) of all the storage form, as the particle density does (0.12 and 1.297 t/m3 respectively). The ash and volatile matter of the three storage form kept stable. However, we found some strange phenomenon as follows: 1) generally, all the net calorific values become bigger as time (the total water values); 2) The range of the total water was the biggest (2.42%) when the corn pellets was stored in the open-air mode, while the range of the particle density was the smallest. So the phenomenon needs further study. The conclusions provide a theoretical basis for the safe storage of biomass pellet fules.