Plastic-Injection-Molding is a very important technology in industry. However, even today, still large amount of manufacturers usually solve mold and molding process problems by trial and error. As the result, quality and cost of the products are the first to be sacrificed. Moreover, with trial and error during molding process or mold development, the mold need to be modified countless times before delivering with patching and unnecessary welding marks, leave the customer an unprofessional impression. The presented project is to explore the effective plastic injection molding process management methodology, through a series of real life examples. First, this paper analyzes plastic injection molding process, optimize mold design parameters, utilizing Computer Sided Engineering (CAE) tool before the mold is actually made. After completing the mold fabrication, Tacuchi method is used to optimize the molding parameters. Finally, the Cpk table is used to analyze quality consistency for optimized injection molding process.