In this study, a gasification process has been investigated systematically by numerical method, in order to obtain design and operational concept for the gasification of RPF. A commercial scale of the facility of up-draft fixed bed gasifier was considered with the ignition by plasma torch. Turbulent reacting flow was calculated with the incorporation of the appropriate flow model for the turbulence in free space and inertial resistance for the porous region of waste loading. Further a detailed thermochemical model was employed for estimating the syngas composition by gasification. This study, focused on the S/C (steam/carbon mole ratio) and ER (Equivalence ratio) to show effective gasification process. Results show that better solution of the combined combustion and gasification process strongly and in a delicate manner depends on both equivalence ratio (ER) and steam and carbon mole ratio (S/C). This optimization of the gasifier is evaluated for the following ER (0.25, 0.35, 0.45), S/C (0.0, 2.2, 3). In this study, the gasification efficiency is the best at ER 0.35 and S/C 2.2.