【Abstract】Based on presupposition theory， this paper tries to show how presupposition is realized in courtroom interaction and how a favorable effect is made for parties in a trial. By using the strategy of presupposition， judges， lawyers and public prosecutors can direct the conversation， make a linguistic trap and create a favorable effect for themselves. It is shown that the strategy of presupposition is helpful for judicial professionals to improve their language skills and enhance their efficiency in courtroom interaction.
　　【Key words】courtroom interaction； presupposition theory； the strategy of presupposition
　　1. Introduction
　　In today’s world，， legal language has been drawn attention by linguists and judicial professionals. Famous scholars in China， such as 杜金榜 （2004） and 陳炯 （1998）， have devoted themselves to legal texts and legislative language. With the development of China’s legal system， the professional skills of the judicial workers need to be further enhanced. A study of the strategy in courtroom interaction can not only offer the judicial workers linguistic guidance but improve their efficiency in handling those cases.
　　Based on civil and criminal cases， this paper tries to study the strategy of presupposition in courtroom interaction. The study focuses on how to use the strategies to make a linguistic trap so that the court debates develop in a way that is favorable for all the parties. It is hoped that this study will contribute to the development of the language skills of judicial workers.
　　2. Introduction to Presupposition
　　The study of presupposition dates back to the philosophical debates about reference and referring expressions. Frege（1952） was the first to initiate this phenomenon. He was interested in the distinction between sense and reference， defined by using a proper name in an assertion presupposes that the name designating something. Frege also observed even though this assertion is negated； the proper name still designates something.
　　Example： （1） Kepler died in misery.
　　（2） There exists a person called Kepler.
　　（3） Kepler did not die in misery.
　　“Kepler” in sentence （1） must designate certain entity in the world. Although sentence （1） does not include sentence （2）， yet it presupposes sentence （2）. Despite that sentence （1） and sentence （3） contradict each other concerning their meaning， they presuppose sentence （2）.
　　The presupposition theory proposed by Frege includes the following aspects：