A method and apparatus for dynamically switching a gateway of a DRNI are provided. The method includes: synchronizing information of main and backup gateways of each portal system between a portal system of a DRNI end point and other portal systems of the present end point; the portal system detecting whether an event which triggers switching the main and backup gateways occurs or not; and updating a gateway of a service or session when the event which triggers switching the main and backup gateways is detected, a portal system in which a new main gateway of the service or session is located starting to forward the service or session via the main gateway, and a portal system in which the backup gateway of the service or session is located stopping forwarding the service or session via the backup gateway.