At present, digital textbooks (DTs) are a key development direction in higher vocational education in China, but research on their application remains limited. To fill this gap, this study adopts the Technology Acceptance Model(TAM), takes the course Digital Electronic Technology as the research context, and evaluates digital textbooks usage effectiveness through a combination of questionnaires, facial recognition, and backend data analysis. It reveals a contradiction in digital textbooks usage: while students show high Behavioral Intention to Use for digital textbooks and recognize their Perceived Usefulness, 34.7% of in-class usage of digital textbook carriers (mobile devices) focuses primarily on non-academic activities. Analysis highlights two key causes. First, defects in Perceived Ease of Use, such as difficulties in task switching, and the suppression of Attitude Toward Use by distractions weaken Behavioral Intention to Use’s ability to drive actual digital textbooks use. Second, insufficient digital textbook functions and classroom management fail to channel high Behavioral Intention to Use into learning-related behaviors. In response, this study proposes a framework of digital textbooks simplification & task-bound usage & time-limited access, which not only provides empirical evidence for resolving the behavioral intention-behavior conversion issue in digital textbooks promotion but also offers references for the integrated application of digital technologies in higher vocational education.