This study investigates the inter-relationships among environmental uncertainty, knowledge transfer, and competitive advantage. Based on 176 subjects from the R&D and manufacturing department of 56 Taiwan semiconductor companies, this paper implements a structural equation model to test the research framework and hypotheses. It finds that knowledge transfer could develop semiconductor firms’ core competence and then build their own competitive advantage. In addition, this study considers that environmental uncertainty is a vital factor during knowledge transfer. Research results indicate that the partially mediated model shows good model fitness for this relationship. In addition, the relationship between environmental uncertainty and knowledge transfer is negative, and knowledge transfer and competitive advantage have a positive relationship. This means that environmental uncertainty could hinder knowledge transfer and lead semiconductor firms to develop knowledge by themselves. Therefore, knowledge transfer to semiconductor firms is very important for technological and knowledge management activity in this rapidly changing industry environment.