With the rapid development of information and communication technology, the amount of information in storage medium is significantly increasing. Just deleting the index file on table cannot really delete the information. Long-term storage of those information may easily lead to data leakage. Therefore, secure deletion of the storage medium is one of the most attractive research areas. In order to address this problem, the basic knowledge about storage medium is introduced in this paper, including the basic structure, the principle of storage and the principle of deletion of the storage medium. Then, some commonly standards of data deletion are analyzed, the characteristics of these standards are studied. Finally, we design and implement a secure deletion prototype system, and the existing data deletion software is tested and analyzed. The result demonstrates that the secure deletion prototype system can safely delete the data in the storage medium and effectively protect users' privacy.