How to synchronize two iPhone?

Use the same Apple ID, and then start the iCloud cloud service and the content to be synchronized.

Here, take the iPhone 7 mobile phone synchronization address book as an example, and the specific method is as follows:

First, click "Settings" on the mobile phone desktop, as shown in the figure.

Secondly, select the "password and account number" option, as shown in the figure.

Third, then open "iCloud" to enter.

4. Then turn on the switch in the "Address Book" column in the iCloud interface.

5. Then select "iCloud Cloud Backup" on the drop-down page.

Sixth, finally turn on the switch of "iCloud Cloud Backup".