Object storage system provides ocean space to hold a very large amount of data objects reliably and guarantee the clients to efficiently obtain their big data. In this paper, we propose a secure provable data possession scheme for object storage system, so as to enhance the security and efficiency through interactive verification and hierarchical structure optimizing. In particular, a new secure protection strategy is presented for detecting data corruption and preventing data loss. Finally, we conduct a statistical experiment evaluation to test the performance and security of our strategy.