In this paper, we propose a parallel multidimensional index structure and range search and k-NN search methods for the index structures. The proposed index structure is nP(processor)-n×mD(disk) architecture which is the hybrid type of nP-nD and 1P-nD. Its node structure increases fan-out and reduces the height of an index tree. Also, the proposed range search methods are designed to maximize I/O parallelism of the index structure. Finally, we present a new method to transform k-NN queries to range search queries. Through various experiments, it is shown that the proposed method outperforms other parallel index structures.