As known to all, blended learning has gathered the merits of both face-to-face teaching and online learning. Much research has already proved that blended learning has positive effects on students' learning outcomes. On the other side, this concept is too flexible and fuzzy to define and master for educators. What factors need to be blended? How to blend them, and what are the key impact factors for blended learning outcomes? The present study aimed to answer these questions. Both qualitative and quantitative research methods were used to collect data from semi-structured interviews of 21 students and questionnaires of 641 students in a Chinese college from 2012 to 2013. The whole research was composed of three stages: 1. The author electively interviewed 21 college students to collect their perceptions of blended learning; 2. Based on literature review and interviews, a questionnaire was designed with 94 items to collect data about learner's perception of blended learning, metacognitive ability, learning interests and self-efficacy. This questionnaire was pretested with 141 students; 3. The questionnaire was revised and retained 52 items in accordance with the pretesting results, and 500 participants were involved in the final survey. Results indicated that six key attributes of blended learning: systematization (teaching arrangements), blending (teaching methods), Openness (instructional resources), context (learning situations), collaboration (collaborative learning) and autonomy (active learning) have significant influence on blended learning outcomes in higher education.