This study investigated the impact of material properties of epoxy molding compounds on wafer warpage in fan-out wafer-level packaging. As there is currently a lack of comprehensive discussion on the various material property parameters of EMC materials, it is essential to identify the critical influencing factors and quantify the effects of each parameter on wafer warpage. The material properties include Young’s modulus of the epoxy molding compound before and after the glass transition temperature (Tg) range of 25–35 °C (EL) and 235–260 °C (EH), coefficient of thermal expansion (α1, α2), and the temperature change (∆T) between ELand EH. Results show that, within the range of extreme values of material properties, ELand α1 are the critical factors that affect wafer warpage during the decarrier process in fan-out packaging. α1 has a more significant impact on wafer warpage compared with EL. EH, α2, Tg, and ∆T have little influence on wafer warpage. Additionally, the study identified the optimized material property of the epoxy molding compound that can reduce the maximum wafer warpage in the X and Y directions from initial values of 7.34 mm and 7.189 mm to 0.545 mm and 0.45 mm, respectively, resulting in a reduction of wafer warpage of 92.58% (X direction) and 93.74% (Y direction). Thus, this study proposes an approach for evaluating the impact of material properties of epoxy molding compounds on wafer warpage in fan-out wafer-level packaging. The approach aims to address the issue of excessive wafer warpage due to material variation and to provide criteria for selecting appropriate epoxy molding compounds to enhance process yield in packaging production lines.