Gasification is one of the promising technologies for thermochemical conversion of biomass. Biomass gasification using high-temperature air/steam has many features superior to those of conventional gasification using low-temperature gases. To improve the conversion efficiency, it is important to understand transport phenomena in biomass gasification and optimize the packaging of biomass before its use in industry. A novel modeling tool has been developed to study biomass gasification process, and it consists of a system-level model and a pore-level model. Effects of feedstock packaging such as initial porosity, particle size, and distribution on the gasification rate will be investigated. The concept to design holes in the feedstock is proposed to increase the gasification rate. It is revealed that optimizing the size of the holes, in the packed biomass can increase the biomass gasification rate significantly.