Although previous research has demonstrated learning benefits for both instructors and students in the web-based collaborative learning environments, one of them major difficulties is the lack of a practical approach to assist teachers in evaluating the knowledge contribution of learners. A novel method of merging multi-modes of assessment and reward mechanism in a collaborative learning system was examined in this study. The developed system has been applied to a learning activity of a web programming and design course and 102 2nd-year college students from two classes were invited to participate in this research. The system logs and assessment results were analyzed through system use over 6 weeks. The experimental results showed not only could the proposed approach provide instructors with feedback, it could also evaluate and improve learning. In addition, learners could easily and efficiently manage their learning outcomes, share knowledge with one another, reflect on and notify others of learning outcomes and learning status, and engage in high-level reflective practices. (Contains 7 figures and 5 tables.)