The paper analyses and explores the function of the modes of theme and rheme in the discourse of english and chinese from the four basic modes of theme and rheme and their expressive forms in the discourse of english and chinese and from their rhetorical function by listing many examples just to help people comprehend the discourse and text more exactly 摘要列举丰富的实例从主位述位四种基本模式，在英汉话语中的表现形式，及从主位述位模式的修辞功能等方面对主位述位模式在英汉位语中的作用进行分析及探讨，从而帮助人们能更准确理解话语及篇章。
