The present invention relates to a method of data uplink synchronization between a mobile terminal and a server. The server modifies the stored address book data one item by one item. The present invention also relates to a method of data downlink synchronization between a mobile terminal and a server. Before the server sends address book data to the mobile terminal requesting the downlink synchronization, it performs item-by-item adaptation of the address book data according to the item's attribute and parameter supported by the mobile terminal. The present invention relates to another method of data downlink synchronization between a mobile terminal and a server. The mobile terminal, according to the received address book data, modifies the stored address book one item by one item. The present invention implements the operation on each item in the address book, the adaptation to the item's attribute and parameter of the address book according to the specific situation of the mobile terminal, and the mapping to each item according to the meaning of the attribute and parameter so as to effectively avoid information loss caused by inconsistent attributes and parameters and the operations on the record.