Compared with the end of Qing dynasty, during the period of the Republic of China, the unification of scientific terms becomes our first priority as a large amount of knowledge swarmed in. As the only official institution for translation, the National Institution for Compilation and Translation made a great contribution to this area. The conclusion of my essay is that the achievement of the National Institution for Compilation and Translation in terms unification was closely related to four reasons: the foundation made by predecessors in this area; the emergence of a good supply of talents; the standardization of terms' compilation and the assistant from other scientific communities.