In this study, the deformation of injection-molded parts with different thickness ratios was investigated. To modelthe deformation inside the injection mold, a constraint boundary condition was assigned to the vertical walls incontact with the molded part during in-mold shrinkage. The effect of the processing parameters on the deformationwas investigated using the Taguchi design of experiments, with four processing parameters melt temperature, mold ?temperature, packing pressure, and packing time considered in the full factorial design. The constraint boundary ?condition considerably affected the deformation behavior of the molded part. Among the considered parameters,packing time, along with its remarkable interaction effect, had the most significant effect. Moreover, it was possibleto determine the optimal processing conditions for minimizing the deformation.