Replica strong consistency maintenance for unstructured overlay networks was studied.Current replica consistency maintenance algorithms was summarized

and a novel replica consistency maintenance algorithm:node heterogeneous degree-based of consistency maintenance algorithm（NHDCOM） was proposed.NHDCOM denoted the replica node capability by node heterogeneous degree（NHD）.It managed replica nodes using Chord protocol and collected those nodes NHD along with a replica heterogeneous degree collection tree（HDCT） built through the finger table-based ring partition method.Moreover

a replica update problem model was abstracted in NHDCOM

and then a minimum delay update-content tree algorithm based on dynamic programming method was proposed to improve the update speed.Theoretical analysis and simulation results demonstrate that this method is more efficient in maintaining strong replica consistency and updating replica nodes for unstructured overlay network systems.