The mobile communication system comprises a host mobile terminal, at least one client side mobile terminal, a SMS server and a PDSN for assigning IP addresses. The method comprises: when PDSN receives IP address, the host mobile terminal sends the invite message to the client side mobile terminal through the SMS server; the client side mobile terminal receives IP addresses from PDSN, and sends the registration message to the host mobile terminal through PDSN; the host mobile terminal renews the list of friends, and sends the renewed friend list to the client side terminal; the host terminal and the client side terminal exchange the image data according to the renewed friend list.