Since the number of data items keys is larger, much higher security is needed in database encryption systems. In view of this question, we propose new key management schemes based on access control and Chinese remainder theorem which makes the management of data items keys convenient. A large number of the data items keys Ki which the user  ui has access to, can be compounded to user class keys

uki when the user applies for the key, then this key is saved. When the user decrypts the data, user class keys  uki  are broken down into key data items using the system tables and the Chinese remainder theorem. The schemes can solve the problems of high time cost on processing data and more system resources occupation, thus improving the efficiency and security of the key management in the cipher text database. Experiments and comparison prove the significant improvement in efficiency and security of key management.