As the sampling data is getting tremendous, more than one sampling points will project into a pixel. This makes point based rendering (PBR) popular. For PBR, the main steps that prominently affect the rendering result are hierarchical data structure, LOD selection method and rendering primitives (triangle, point, surfel [1]). In this paper, we generate a hierarchical structure with tight-octree, and store the vertex and bounding box information for each level. Then we propose a new method to do LOD selection based on the distance between the model and the viewer and the pre-calculated bounding box information. We have tested different polygonal models with million vertices on our system and the results demonstrate that the method is interactive in real time.