Abstract: The ROAM algorithm is not suitable for out-of-core rendering because of inter-block coupling, and is inefficient for recursion.With a high compression ratio of nested regular grids algorithm, the paper proposes a parallel LOD algorithm using matrix structure.This algorithm adopts matrix structure to eliminate the inter-block coupling, and is suitable for out-of-core rendering.It also eliminates the recursion to improve performance, proposes the parallel algorithm and uses CUDA to accelerate the processing.Experimental results show that the algorithm is suitable for visualization of out-of-core terrain data, and has a 2~20 times speedup compared with traditional ROAM algorithm.