Abstract: The paper proposes a real-time tiling method for extra-large scale terrain rendering. The core idea is based on a loading-on-demand technique which dynamically loads visible parts of the terrain model, then titling and rendering. The method solves the boundary match problem for adjacent terrain blocks in dynamic loading which avoids “cracks” and rebuilds the whole terrain identically and seamlessly. Using this method, real-time walkthrough of 144 sq.km. terrain data is implemented on platform of PIV 2.4GHz, 512MB, ATI 9550. Experimental results show that the efficiency of algorithm is high on both time and memory and the method supports real-time visualization of extra-large scale terrain. It is also a functional module in our newly-designed Game Engine.