Arrangement and management for learning materials and awareness processing are key problems in the Web-based collaborative learning environment. In order to provide reasonable learning navigation and flexible awareness processing in a collaborative learning environment, a nested knowledge space model is presented, which includes concepts such as knowledge domain, four kinds of relations among knowledge domains and knowledge space, etc. Based on this model, a Web-based collaborative learning environment is established and learning materials in the system are organized and managed, which can help users to get their needed learning documents. To get rid of users' isolated feeling in the collaborative learning environment, a multi-levels awareness processing model based on the nested knowledge space model is presented, in which there are two awareness methods: the multi-levels awareness space method and the customized monitor method. In addition, information filter and privacy protector are provided, which can filter redundant information and protect users' privacies effectively. The prototype system shows that the methods can make learners find their learning goals and their materials easily and finish their learning quickly through awareness of other learners' information and mutual discussions.