It has been proposed that there are two alternative strategies for bilinguals to translate between languages, i.e. "transcoding", which takes the "shortcut" linking translation equivalents between the source language (SL) and the target language (TL), or "transphrasing", which takes the "long route" involving a monolingual processing of meaning in the SL, a non-verbal conceptual level, and then a monolingual processing of meaning in the TL (1-4). This study examined the neural mechanism underlying these two translation strategies in the context of Chinese to English simultaneous interpreting (SI) by using optical brain mapping techniques. In particular, brain activation patterns associated with the two forms of bilingual processing are compared with those related to "code-mixing", which is a strategy that probably has little to do with bilingual processing but available to simultaneous interpreters in certain contexts. We discovered that "transcoding" only elicited significant and almost immediate brain activation in the Broca's area, whereas "transphrasing" produced more extensive and stronger activation across the whole left prefrontal cortex as compared to "code-mixing". This pilot study, which provides neurological evidences for the "shortcut" and the "long route" that bilinguals utilize when translating between languages, will definitely pave a new avenue for better understanding of the cognitive mechanism underlying translation, bilingual processing and speech production in general.