In fire community, predicting large scale fire behavior is the main target of researches. Flame spread from one area to another is one of the most important fire behaviors which may lead to destruction of buildings, jungles and etc. Therefore, in recent years, flame spread of solid is attracting many attentions and many studies focused on these phenomena. Pyrolysis modeling is one of main aspects in flame spread simulations via computational fluid dynamics (CFD) method. A 1D pyrolysis model has been developed based on OpenFOAM, an open source toolbox in order to enhance FireFOAM solver potential to simulate flame spread on solid materials. The prediction of developed pyrolysis model has been compared with empirical data for surface temperature and mass loss rate of PMMA. Uncertainties in experimental measurements caused for input parameters not to be unique, thus, a particular set of model input parameters have to be determined to reach an acceptable agreement between pyrolysis model and experimental results. Using optimization method is very common in that matter. The non-linear nature of problem and input parameters being numerous would make optimization calculation expensive. In this article, the effects of input parameters (as PMMA properties) have been investigated to firstly, to observe the effects of material properties on pyrolysis process. In the other hand, the most influential properties are introduced in order to reduce computational costs in optimization process by optimizing only these properties.