Abstract: It has been ten years since the concept of blended learning came out. Blended learning is now widely applied in educational institutions and enterprises all over the world. Moreover, it is found that it improved students' learning outcomes significantly. The purpose of this research is to find principal influencing factors by qualitative study. 21 university students who have personal experiences of blended learning in a Beijing college were interviewed. The research found that learning resources, learning management system, instructor's involvement, collaborative learning activities and learning support all have significant impacts on students' perceptions of blended learning and their learning outcomes.