Over the past few years, the prevalence of web-based applications in school and at home makes learning and teaching through the Internet become an inevitable way in education. With great potentials for enriching all kinds of educational applications, web-based instruction is becoming an impressive apparatus for learning resource delivering. In this study, an asynchronous web-based language learning (AWBLL) system is employed in a vocational-technical college in Taiwan to support undergraduate English as a foreign language (EFL) learning. Drawing on the concepts from theory of reasoned action, technology acceptance model and social cognitive theory, this study proposed a comprehensive model and developed an instrument for measuring students’ intentions to use AWBLL Systems. The research findings indicate that students in EFL show great readiness to and positive intentions towards the system for EFL courses and exposed a possible benefit from its use in the long run. However, they also convey some negative opinions of the AWBLL system, suggesting additional improvement of the relative underlying factors of AWBLL technology. The results can proffer useful suggestions for web-based language learning, as well as serve as instrumental guidelines for web-based system to be effectively implemented with care to avoid attenuating students’ interests and activations.