The size of 3D model reconstructed based on oblique photography is always too large to load into Unity3D efficiently and robustly for roaming. To solve this problem, we propose a novel roaming method for oblique photography threedimensional models in Unity3D. The method can quickly load large-scale oblique photography model in Unity3D and realize fluency virtual roaming. Firstly, different level of detail models are generated by using LOD (level of detail) technology and divide the LOD models into blocks with same size. Secondly, we load the entire low LOD model as a panoramic view of the scene and load little high LOD model blocks around the location of viewpoint dynamically while roaming. A Nine-palace mode is adopted for high LOD model blocks selection strategy. Finally, a coroutines and asynchronous loading methods are used to further improve the roaming process. The experimental results show that our method is faster than Acute3D Viewer in the visualization of oblique photography model.