In the modeling industry today, pressure molding product shape technology is quite important. Plastic items are molded under pressure using a very complex process that results in several defects, such as warping, incomplete filling, and burning black marks. Pressing plastic items with narrow wall thickness is particularly prone to partial filling problems. Many manufacturers rely on their experience and experimentation to determine compensation for various technical parameters, such as melt temperature, injection pressure, and injection velocity. However, technical specifications are not optimized, leading to wasted time. In this study, the plastic filling ratio of a thin-walled injection mold was calculated by simulation using Creo 8.0. The plastic filling rate in the mold cavity was estimated using the Taguchi method. The findings from the Creo 8.0 module simulation demonstrate that the boundary conditions significantly impact the rate at which plastic fills the cavity of a thin-walled plastic injection mold. This conclusion is supported by analysis of variance, regression, and noise analysis. For the thin-walled plastic injection mold, a plastic filling ratio of 0.59 is identified as the optimal value. Creating mathematical models is a prerequisite for using optimization techniques to maximize the resin flow filling capacity. However, if the mathematical model's inaccuracy is excessively high, the results will be unsatisfactory. Therefore, this research will focus on using the Computer-Aided Engineering (CAE) method to predict mold filling outcomes. Specifically, by simulating the plastic expansion in Creo 8.0, the study aims to adjust the width between the upper and lower molds for the electrical socket cover product to forecast the plastic filling rate in the mold cavity.