Disclosed is a method for transmitting a packet through a plurality of physical links in a mobile communication system in which a base station controller (BSC) is connected to a base transceiver system (BTS) through the plurality of physical links. The method includes the steps of determining whether a specific service uses at least two links, when there is transmission data for the service; setting up a sequence number in the transmission packet, when the service uses at least two links; and transmitting the packet through a link selected from the two links. The determining step is performed when there is transmission data for the service, and the setting step is performed when the service uses at least two links.