Synchronization is one of the key technologies in maintaining the consistency of replicated mobile database systems. A lot of research has been focused on transactional synchronization schemes in recent years and many models and algorithms have been proposed. However, existing transactional synchronization schemes have some limitations. In order to solve these problems, a new synchronization scheme, double-timestamp transaction-level synchronization (DTSTLS) model, is put forward in this paper. DTSTLS model uti;izes a three-tire architecture.Therefore existing database products can be used as its database server,which improves the flexibility and extensibility of the system.As an asynchronous group replication method,DTSTLS model allows allows users to access local replicas of the database and to locally submit mobile transactions when the system is disconnected.The locally committed transaction are sent to the syuchronization server for conflict reconciliation and synchronization when the system is reconnected.Mobile transactions thst have executed conflicting operations will be aborted,and only those mobile transactions that do not violate the consistency of the database system can be globally committed.In this way,the consistency of the database system is ensured.Besides,Besides,Besides,through a novel timestamp strategy,DTSTLS model cuts down the resource resource consumption and reduces the communication costs.Detailed simulation experiments are carried out,and the results show that the proposed methodology not only ensures the serializability and consistency of the mobile database system,but also reduces storage consumption and communication cost.