The present invention relates to register a cloud account and allocate a cloud storage space. Information about contact people in the directory at each user's terminal is backed up to the cloud storage space for each user's terminal. The contact information of each user's terminal is stored in its cloud storage space. Once the contact information is changed, the changed contact information is updated in the cloud storage space for each user's terminal and simultaneously in the cloud storage space for all of the contact people in the directory at the user's terminal. The updated contact information about the user's terminal can be downloaded from the cloud storage space. The information about the contact people among the user's terminals can be transferred with one another.