Multi-Dimentional vectors indexing is one of the key technologies in multimedia database systems. This paper focuses on the dynamic indexing structure based on the vector space. An ER-Tree indexing structure is proposed which is efficient for medium and high dimensional vectors. In the ER-Tree, the efficiency of retrieval could be improved by the ways of partition of the vector space with hyper-sphere and R*-Tree s re-insert technology introduced to enhance ER-Tree s capability to represent the data-sets'features.By introducing safe-inserted-node and safe-deleted-node concept into the structure,the performance of tree creation is reenforced.The algorithms are also given for the creation of ER-Tree.The empirical test test results show that(1)the tree creation algorithm proposed is about 10 times faster thanR*-Tree.(2)the effectiveness of retrieval is highly improved.