Abstract: This paper uses the triangle bitree data structure，divides the terrain with the suitable size，so only deal with local terrain each time；proposes a mixed method of reasonable clip with bounding sphere and bounding cone，and produces adaptive levels of detail in accordance with the change of viewport and the corresponding vertex error.Thus reduces the number of redundant operations，avoids the problem of the occurrence of cracks and jumping feeling in details conversion，reduces the amount of data processing and the computational complexity.