Injection molding is one of the commonly used processes for plastic part production due to numerous advantages, such as rapid production, complex shape modability, and material selectivity. However, highly experience-based conventional production restrains the industry development. Company know-how loses with the experienced operator's left. On the other hand, molded part quality was only based on the operator check. There is without an effective solution to maintain its stability and defect-free adjustment. How to establish a scientific injection molding setup and quality control method is an urgent topic. This study established a practical method for quality monitoring based on the pressure-volume-temperature (PVT) property. The PVT processing path control for scientific molding parameter setup was investigated. This is not only the method for parameter optimization but also the molded part quality control. Three major qualities were discussed in this study, including product weight, shrinkage, and warpage. By the molding condition optimization, three qualities improved up to 1%, 41.9%, and 9.2%, respectively.