In order to overcome the problems of large amounts of calculation and low operating efficiency of ray tracing algorithm, a ray tracing acceleration structure based on the octree adaptive volume merging (OAVM) is proposed. Through gathering blank nodes of an octree model as a bounding volume adaptively, this structure can reduce the intersection number between ray and blank nodes as much as possible. Based on the characteristic that OAVM is a multi-level octree structure, an algorithm with the Morton code to encode all the nodes at different levels is proposed. The storage method and neighborhood search algorithm used in this structure can reduce the amount of pointers and avoid the recursive search effectively. In the meanwhile, the algorithm deals with the problem of partial update a in large scale dynamic scene effectively. Based on the idea of Liang-Barsky algorithm, the calculation speed of intersection test for rays is improved. The experiment results indicate that, compared with traditional algorithms, the proposed algorithm can reduce the total number of pointers by 54.45% averagely. The time of ray intersection test is reduced by 52.37% averagely. The ray intersection test time is decreased and the scene rendering efficiency is improved.