Knowledge Grid is a platform that enables uniform and effective knowledge sharing and management across the Internet. Based on this platform, this paper proposes a cooperative learning environment KGCL. It supports the knowledge-level cooperation between human and computer, and enables the enrichment of not only the resources in the Knowledge Grid but also the knowledge of users by means of knowledge refinement, knowledge reuse and drawing together online participants. Currently, the prototype of the KGCL has been implemented and is available for use online. Experiments show that the environment can promote the effectiveness of teamwork.