This chapter selected plastic injection molding to investigate molding real production. Plastic products penetrate plastic injection forming. Recently, 3C products have required light and thin materials. In traditional plastic injection forming, several parameters can influence mold product precision, such as warping, sinking and residual stress, surface quality, size deviation, and shrinkage rate. Therefore, this chapter examines the sheet forming for plastic injections. The experiment investigates the runner gate number and appearance influencing plastic injection finished products. First, mold flow analysis software was used to search for optimum parameters. The primary test offers various parameters in runner and pouring gates and examines their influence on surface roughness in plastic injection thin sheets. The experimental results show useful insights into the optimal processing conditions for plastic injection forming of thin sheets and offer a reference for the industry.