The effect of too much overhead caused by fixed neighborhood state update cycle on the whole network performance has been greatly alleviated by a neighborhood state dynamic update ( NSDU ) algorithm proposed for MANET in this paper.A local topology flapping metric ( LTFM ) has been established based on the changes of link connection to achieve the measurement of stability.The loop control theory has been adopted to establish the control model of the neighborhood state,so as to set up the mapping relationship with the topology change,based on which both the neighborhood state information exchange and the timeout of link with neighbors involved will be adjusted dynamically according to NSDU to ensure that the update cycle would regulate with the network environment in order to achieve the purpose of reducing the control overhead.The simulation results on NS2.34 with different nodes velocities,traffic generating rates and the network node densities shows that adopting NSDU,no matter based on a table-driven protocol or a on-demand one,would reduce the overhead effectively while hardly bring any obvious impacts on metrics of packet successful delivery rate and the average endto-end delay as well.