Abstract: The data encryption can be employed to protect the data in a storage device, but it cannot be employed to hide the client's data access patterns from an untrusted server in cloud storage applications. The adversary can get the client privacy from access patterns. The paper proposes a new oblivious RAM construction, Using the data element position mapping table and bitmap of storage blocks achieve the oblivious access of data. Each data element has two backups that are stored in two files. When a data element in a file is destroyed, the data element may be recovered from the other file. Each data element request of the client will generate O(1) read and write operations on the server with a small amount of client storage and O(n) server storage.