Simultaneous interpretation (SI) means that the interpreter keeps, without interrupting the speaker, interpreting the speech of speaker to the listeners. Its best merits are embodied by high efficiency, continuous talk and better understanding of listeners to the whole speech without interfering with or interrupting the idea of speaker. Simultaneous interpretation is a currently worldwide popular method of translation which is rather technical and professional and often employed by formal international conferences. Nowadays, 95% of international conferences adopt the simultaneous interpretation. The speaker talks in a continuous manner and the interpreter makes interpretation while listens, controlling the interval between translation and speech within three or four seconds up to ten seconds. The competence of interpreter highly dominates since the translation is to be done only in the break between the two sentences by the speaker. Simultaneous interpretation is also called synchronous interpretation.

Simultaneous interpretation is a kind of interlinguistic conversion of extreme difficulty and close restraint by time. It asks that the interpreter shall, while recognizing the source language, quickly forecast, comprehend, remember and translate the information of source language and design, organize, express, monitor and correct the target language, and synchronously present the version of target language. Therefore, simultaneous interpretation is also called synchronous interpretation. In many international conferences, the simultaneous interpreters, by virtue of their lightning mind and amazing skills, succeed in overcoming the problems in energy shortage and attention distribution of brain due to the intersection, superposition and interference of multitasking, well coordinate listening and speaking and make themselves as noticeable as the source language speakers. According to the AIIC (International Association of Conference Interpreters) rules, the interpreter is deemed as qualified if only he/she translate 80% (possibly 90% or even 100%) of speech content by the speaker. Considering that some people get a high speaking speed and only talk with all attentions to his own mind or with an accent, the interpreter have to go all out utilizing all his knowledge and experience. Since few speakers would lower their speed to favor the interpretation, the interpreter is apparently required of excellent competences.