Dong Gang are the biggest fresh tuna market in Taiwan. This thesis deals with the social networks in Dong Gang tuna market and how they affect the tuna market in Dong Gang. This thesis finds that although Dong Gang tuna market has public auctions, the transactions and exchange of information are highly shaped by social networks, especially in the Bluefin Tuna season that starts in April and end in June. Actors use social networks to avoid risk, control prices and maintain the quality of purchase. On the other hand, the status of actors, which is highly influenced by the licenses from the state, also has significant impacts. There are two kinds of license in Dong Gang tuna market; one for domestic market and one for export. Actors with higher status buying fish firs. This research recognizes that the market is embedded in social structure of economic sociology, and explains the dual meaning of the market: entity and concept. It also points out how local social networks shape deal of market. On the other hand, the price of Japanese tuna market influences Dong Gang tuna market; in other words, the Dong Gang tuna market is part of global tuna market leading by Japan, and the state uses license to control. That is, the Dong Gang fish market consists of local social networks, but also connects with state and global tuna market.