In this paper, we present an unstructured peer-to-peer network called GridMedia for live media streaming employing a push-pull approach. Each node in GridMedia randomly selects its neighbors in the overlay and uses push-pull method to fetch data from the neighbors. The pull mode in the unstructured overlay which is inherently robust can work well with the high churn rate in P2P environment while the push mode can efficiently reduce the accumulated latency observed at user nodes. A practical system based on this framework has been developed. And the performance evaluation of our system which is established on PlanetLab [8] demonstrates that the pull-push method in GridMedia achieves good qualities even in high group change rate. Furthermore, our system was adopted by CCTV to broadcast the Gala Evening for Spring Festival 2005 through the Internet and attracted more than 500,000 users all over the world at that night with the incredibly maximum concurrent users of 15,239. Categories and...