Provided are a method and a system for transmitting mobile IP packets without loss. The method includes the steps of storing, by an old radio access station, packets that are not transmitted to a mobile terminal when a handover indication message is received, and creating, by the old radio access station, a tunnel to a new radio access station, and transmitting the stored packets to the new radio access station via the tunnel when a link-layer handover procedure is completed. Thus, upon the handover of the mobile terminal, IP packets directed to the old access control router and the old radio access station are stored in the buffer and then transmitted via the tunnel after the handover, thereby preventing loss of packets during the handover. Thus, yield cannot be degraded upon the handover and seamless network connection service can be provided.