本文结合汉语史研究,从词义演变和语法位置两个角度入手,试图讨论条件连词“但”的形成过程。我们认为,副词“但”的“仅、只”义为条件连词“但”提供了语义基础;同时,“但”在句子中所处的句法位置为副词向连词的转变提供了理想的语法环境。条件连词“但”的形成是语义、语境、句法位置的变化以及人们认识上的引申和迁移作用共同作用的结果。 Combining with the research of Chinese history, this article attempts to discuss the formation process of conditional conjunction “but” from two perspectives, meaning evolution and grammatical position. In our opinion, the adverb “only ” has the semantic basis for the conditional conjunction “but ”. Meanwhile, the syntactic position of “but ” in the sentence is the adverb to the conjunction The transition provides the ideal grammar environment. The formation of conditional conjunctions “but ” is the result of the common action of semantic, context, syntactic position changes and people’s cognitive extension and transfer.