Abstract: Yan Yuan is a very important practicalist from Late Ming Dynasty to Early Qing Dynasty.On the relation of righteousness and benefit, he put forward that the reasonable benefit should be approved and rational merit should be conformed with morality and righteousness.In accordance with predecessors'thought, he paid more attention to the importance of unity of opposites between benefit and merit.Because benefit and righteousness are just like the two sides of one coin, they shouldn't be treated separatedly.Of course, this proposition is a perpetual topic.We hope to exploit more benefit inspiration for present age.