In this study, rice husk gasification process, in a bubbling fluidized bed gasifier, was investigated. To simulate gasification process, a kinetic model was used which comprises chemical kinetic and flow hydrodynamics. This model is based on two phase fluidized theory, in which, it is assumed that there are two phases in the bed which there is mass and energy transfer between them. These two phases are bubble phase and emulsion phase (containing solid particles). In this model, it is assumed that temperature remains constant along the reactor. Results had a satisfactory agreement with the existed experimental studies in the literature. A parametric study carried out and the effects of different parameters were investigated. The results revealed that changes in the bed diameter have a negligible effect on the gasifier performance. On the other hand, increment of reactor temperature and bed height improve gasifier efficiency but, biomass humidity and inlet velocity of gasification agent, affect gasifier efficiency diversely. Also, increase in the air to fuel humidity and the diameter of the bed particles, at first, raise the efficiency, however, decreases the efficiency in continuation. Finally, in order to obtain the maximum efficiency, the proper operational condition was specified.