Abstract: Abstract: This study aims to explore the impact of background information (BI) on the translation quality of metaphorical expressions (MEs). We designed a between-subjects experiment in which 60 Interpreting Course students were cross-grouped into a control group (CG) and an experiment group (EG). Both groups were asked to sight translate a speech with ten MEs, but only EG members were given materials introducing relevant BI beforehand. The research triangulates data from the recordings of sight translation outputs, the transcription of the recordings and the subjects’ retrospective interviews. The paper concludes with two main findings: 1) the acquisition of BI markedly betters the “fluency” of the EG’ delivery by shortening the processing time and reducing the silent and filled pauses; 2) the acquisition of BI discernibly reduces the difficulties of the comprehension and reformulation of MEs, and thus increases the “faithfulness” and “accuracy” of the translation products.