With the development of computer network， the security problem of database inter-network access is becoming more and more serious. In order to enhance inter-network access security of database application system， a database security proxy technology is introduced in the paper. The database inter-network access system is implemented by using the remote method invocation（RMI） and Java database connectivity（JDBC） technology. The system proposed supports common databases and has fine generality. It can also support the security filtering based on IP， port， mandatory access control（MAC） address and structured query language（SQL） semanteme. Testing results show that the database security proxy system can satisfy the demand of database inter-network access and enhance the security of inter-network access of database application system.