Pause is often found among interpreters, especially among student interpreters, and could be an indication of a stressful cognitive process during interpreting. Research in sight translation has shown that syntactic and lexical difficulties in the source texts could cause hesitation pauses, but how training would impact student interpreters’ pauses during sight translation has not received focused attention. In this project, we aim to gain insights into the training impact on trainee interpreters, in particular, on their pauses during sight translation. The paper reports the findings of a longitudinal study over a period of two semesters, comparing the salient pauses (2 s or longer) during sight translation by a group of interpreting students with that of a control group. Participants were asked to sight translate texts containing nominal groups of varying complexity, which have been identified as a challenge in translation from English into Chinese, while their voice data were recorded and later assessed by independent markers. Salient pauses of varying lengths are identified and grouped as dependent variables. Syntactic complexity, Experiment time, and Group are identified as independent variables. Mixed-effects modeling was used to investigate if students majoring in translation and interpreting (T&I) show a different pause pattern from their non-T&I counterparts, and if training has had an impact on the occurrence of pauses. Furthermore, the grammatical positions of the over-long pauses (5 s or longer) have been analyzed to explore possible explanations behind the occurrence.