Transcutaneous vagus nerve stimulation (taVNS) offers an effective, non-invasive alternative to implantable vagus nerve stimulation and it is considered to be a promising cognitive modulation tool. However, at present, the effect of taVNS on working memory is not clear, Simultaneously, the potential pupillary responses stemming from taVNS require more empirical inquiry. Herein, we investigated the influence of taVNS on working memory capacity and its link to pupillary responses during the change detection task. A sham-controlled, randomized, crossover-designed experiment was applied to 16 participants. Within each session, participants received a Sham or Active taVNS stimulation for 12 minutes and then achieved 3 blocks of change detection task. Each trial exceeds for 5s. The pupil and behavior responses were recorded during the task. We hypothesized that Active taVNS can improve the performance of the change detection task and influence the pupil corresponding to different numbers of target stimuli. For the results, we observed no significant modulation of working memory capacity by taVNS but did note distinct alterations in pupillary response (mean amplitude and extremes) during specified intervals in the change detection task. These findings point to an underexplored avenue of research into the neural or psychological processes affected by taVNS and provides a new insight for taVNS to modulate working memory capacity.