The current methods for process quality evaluation are introduced. A new quality-oriented statistical tolerancing approach for assuring predetermined process quality and product quality is developed on the basis of PCI-based (process capability indices based) statistical tolerancing, which can be used as a guideline to process design and process monitoring. The standardized quality indices that can quantitatively represent process (or product feature) quality and a standardized representation of statistical tolerance zone will be developed. A new statistical tolerance (ST) model will also be developed based on the above points. The technique as the results of the research will have a significant impact on manufacturing industries to improve their competitiveness by properly design and directly assure the quality of product or key-process.