In Computational fluid dynamic (CFD) models of pulverized coal combustion, which require the consideration of complex phenomena, simplified char combustion sub-models have become necessary for computational efficiency. There are several common assumptions embedded in pulverized char combustion modeling when using commercial CFD codes. We sought to quantify uncertainties that arise from these typical char combustion modeling assumptions based on the single-film apparent char kinetic model often used. The modeling assumptions examined include the exception of the Stefan flow effect, the depiction of CO species as the sole char oxidation product and the constant particle size with reaction progress, and the use of questionable rate parameters irrespective of the considered model concept and coal type. The calculated char mass loss and particle temperatures were investigated to evaluate these modeling assumptions.