The present invention relates to the field of network communication technologies, and discloses a method, a device, and a system for establishing an on-demand route. The method includes: determining that a stable route needs to be established; establishing the stable route and recording a route entry corresponding to the stable route in a route table; determining an effective time of the stable route, in which the effective time of the stable route is longer than the effective time of another common route; and performing an aging operation on the route entry according to the effective time of the stable route.