Abstract: An opportunistic network is a type of challenged networks,which has not any stable end-to-end delivery path between source nodes and destination nodes,and the messages are transmitted by the “store-carry-and-forward”paradigm when message-carrying nodes encounter other nodes until they reach the destination nodes．In this paper,we design a information collection and message transmission system--BlueChat--for opportunistic networks by Bluetooth protocol.On one hand,it collects information of node contact for building routing table,mobility model,community detection,routing protocol and QoS strategy research．On the other hand,it transmits messages through different message queue management strategy for special circumstances demand．Performance of this system is tested last for three months and more than fifty nodes involved．Ninety five percent of the messages is delivered and it could meet the message transmission needs of opportunistic networks.

Key words: Opportunistic network,Information collection,Message transmission,Store-carry-and-forward,Queue management