Abstract: Large meshes are becoming commonplace with the advance of 3D scanning, scientific simulation and CAD technology. While there are many algorithms proposed to simplify these large meshes, the time of simplification process is usually very long, especially for those algorithms based on iterative edge collapse. To address this problem, we propose two parallel schemes to speed up simplifying large meshes on a PC cluster. The first parallel simplification scheme partitions a large mesh into small sub-meshes, simplifies these sub-meshes in parallel in an in-core way and finally stitches the simplified versions together. The second scheme generates multiple mesh streams, applies stream simplification to them in parallel in an out-of-core way, and composes the final simplified mesh streams. We have implemented these two parallel simplification schemes and the experimental results show that our methods are able to speed up the iterative simplification of large meshes by a factor of 8 to 19 on a cluster of 24 PCs.