This study investigates the effects of different display modes of video captions on mobile devices, including non-caption, full-caption, and target-word modes, on the English comprehension and vocabulary acquisition of fifth graders. During the one-month experiment, the status of the students' English listening comprehension and vocabulary acquisition was evaluated on a weekly basis. From the experimental results, it was found that the learning achievement of the English target-word group was as good as that of the full-caption group in terms of vocabulary acquisition, while both groups outperformed the non-caption group. When the students' learning preferences were taken into consideration, the visual style students in both the English target-word group and the full-caption group showed significantly better learning effectiveness in terms of vocabulary acquisition than those in the control group. Furthermore, in terms of listening comprehension, the students in all three groups made remarkable progress.