A comprehensive process model is developed to simulate municipal solid waste (MSW) gasification in a bubbling fluidized bed using an Aspen Plus simulator. The model is based on a combination of modules that the Aspen Plus simulator provides, representing the three stages of gasification (devolatilization, partial oxidation, and steam reforming). The restricted equilibrium method is used to correct the deviation caused by uncompleted equilibrium of gasification system. Effects of operating parameters, including gasification temperature, equivalence ratio (ER), oxygen percentage in the enriched air (OP), MSW moisture content, and steam/MSW ratio (S/M), on the syngas composition and gasifier efficiency are analyzed. Higher temperature favors the production of H-2 and CO and leads to higher gasification efficiency. Increasing ER improves the CO yield and the carbon conversion of MSW at lower ERs. The optimal value of ER for air gasification of MSW in this study is found to be 0.35. The use of enriched air elevates syngas heating value and gasification efficiency by increasing the concentration of combustible components, but shows little improvement at temperatures higher than 900 degrees C. Higher moisture content degrades the syngas quality and cold gas efficiency. Steam injection results in higher H-2/CO ratio and gasification efficiency. Optimal S/M value shifts from 0.5 to 1.0 with an increase in OP from 21% to 100%.