Database technology is one of the most widely applied computer technologies, its security is becoming more and
more important. This paper introduced the database security, network database security level, studies the security
technology of the network database, analyzes emphatically sub-key encryption algorithm, applies this algorithm into the
campus-one-card system successfully. The realization process of the encryption algorithm is discussed, this method is
widely used as reference in many fields, particularly in management information system security and e-commerce.