The unit of translation has been the focus of debate through the history of translation. Barkhudarov suggests six levels of UT, each level could serve as unit of different levels of translation. Many Chinese translators also expressed their opinions on this issue, but there is no settled answer yet. This paper tends to make a distinction between different texts: ordinary and special. Ordinary ones can adopt the UT of paragraph, while special ones should adopt special UTs according to their own characteristics.