A method for optimizing routes includes: receiving a route optimization request that includes a network address reallocation indication, wherein the route optimization request is sent by a User Equipment (UE) when a first Packet Data Network (PDN) connection exists between the UE and an old gateway; and triggering establishment of a second PDN connection between the UE and a new gateway according to the network address reallocation indication. Computer program products and computer-readable storage media corresponding to the method for optimizing routes, an MME, a system for optimizing routes, and a UE are also disclosed herein. Through the embodiments of the present invention, an after-route-optimization PDN connection is established in the process of route optimization, and two PDN connections can be established for one access point at the same time.