The integrated circuit (IC) packaging and testing industry is an important link in the semiconductor industrial chain that may decide the success or failure of the foundry industry. The purpose of this study was to compare the competitiveness of the packaging and testing industry in the rear section of the foundry process in Taiwan. Starting from the financial data of six listed companies and using Grey theory, this study summarizes their five factors of competition: scale, growth, profit, efficiency and risks. The study confirmed that the model is able to effectively compare the competitiveness of corporations in the same industry.