How to consider transmission loss cost in generation right transaction is an important issue in ensuring transaction reasonability and effectiveness. To solve this problem， the advantages and disadvantages of the existing generation right transaction model are analyzed， and an improved centralized matchmaking transaction model is proposed to adapt to middle-and long-term transaction. First， the least squares B coefficient method is used to determine the quantitative relationship between transmission losses and transaction quantity. Then the social benefit maximization model considering transmission losses cost is developed， and by solving this model， the total generation of each seller and buyer is obtained. Finally， with the generation volume agreed on by each seller and buyer as constraints， a mathematical model for the matchmaking transaction is developed. An IEEE 30-node system is used as an example to analyze the characteristics of the proposed transaction model. The analysis results prove the rationality and efficiency of this model.