Abstract: The randomness,mobility and disconnection are the characteristic of opportunistic networks.Then there are some similarities of human transmitting messages in human social networks.The traditional algorithms,in social networks,have not acquired good result because of changing application environment.Thus,this paper designed an algorithm——optimal dynamic cooperation tree algorithm when it is in randomness,mobility and disconnection environment.According to find dynamic topology structure,and establish dependability,usability,decline factor,we could count weight of this topology structure,and then obtain the optimal objects and paths.In the light of simulation,we compared it with classical algorithms.This algorithm acquires good result.

Key words: Opportunistic network,Algorithm,Cooperation tree,Weight,Dependability,Usability,Decline factor