Abstract: The key of the interlingua-based MT system is the design of the interlingua. In this paper, the design of the interlingua in ICENT （an interlingua-based Chinese-English natural language translation system） is introduced, which balances the proportion between the grammar and semantic content according to the practicability. It describes the sentence’s structure through describing the grammar relationship among words. Now this interlingua is used in ICENT and the results are satisfactory.