The present invention discloses a flow table generating method and apparatus. The method includes: obtaining, by an SDN controller, a user data packet processing manner of a VAS server that is sent by a VAS server information collector; generating a flow table according to service chain information of a user data packet, the user data packet processing manner of the VAS server, and a 5-tuple of the user data packet; and sending the flow table to an SDN switch, so that the SDN switch can send the user data packet to a corresponding VAS server according to the flow table, thereby implementing access of the user data packet to a related VAS server in a case in which a VAS server modifies a 5-tuple of a user data packet.