The excessive signaling delay of the traditional handover process in Ultra-Dense Network（UDN） leads to the increase of the total delay of the handover

which results in the degradation of user experience quality. This paper proposes an ultra-dense network mobility management algorithm based on the combination of Software Defined Networking（SDN） and Network Function Virtualization（NFV）. The algorithm presents a network architecture model that combines SDN and NFV

which adapts to ultra-dense networks. Based on this

an optimized handover signaling process is proposed and a mathematical model is built for performance analysis. The simulation results show that compared with the traditional algorithm

the algorithm can reduce the total delay of handover.