The invention discloses a one-card-two-number implementation method and system for a China Telecom number and a foreign operator number. The method comprises the following steps: signaling network routing setting: an overseas multi-number platform is in butt joint with two sets of networks through a VLR/VMSC entity; overhead user flow setting; the auxiliary number activates forwarding function setting of the main number; deactivating the setting of the forwarding function from the auxiliary number to the main number; setting an auxiliary number answering process; and the auxiliary number receives short message flow setting. According to the one-card-two-number implementation method and the one-card-two-number implementation system, a China Telecom overseas MVNO mobile subscriber number isused as a main number; one or more China Telecom numbers are bound as auxiliary numbers, so that the user experience blank of the mode that the main number is an overseas telephone number bound with acontinental auxiliary number is filled, and the user can conveniently answer domestic calls and receive domestic short messages with the main number overseas and roam with the continental auxiliary number from the continental.