In this study, in silico model for three-point bending analysis of composite resins (CR) containing silica filler was designed. Relationships between volume content of the silica filler and flexural strengths of CR were determined by combination of mathematical model and finite element analysis. The flexural strengths reasonably increased as the increase of filler contents in in silico model, and the predicted values by simulation were consistent with those of the commercially available CR. Our results suggested that computer analysis can be a useful tool to optimize the compositions and structure of CR to increase their mechanical properties.