It is important to link sounds in English to speak naturally and fluently like native speakers; however, Vietnamese students often encounter the problems of sound linkage. This study aims at finding out whether to use dubbing documentary films on improving linkage of sounds for 1st year English majors. The specific objectives are to evaluate the impact of dubbing documentary films on students’ sound linkage capacity and to collect the students’ feedback with regard to their attitudes to dubbing documentary film activities, the benefits and possible solutions to enhance the effectiveness of dubbing documentary film technique. The study was carried out using quasi-experimental research design and survey. The participants in the study consist of 42 students in which 20 students were selected randomly to participate in the experimental group (dubbing documentary films), and 22 of them were assigned to the control group (non-dubbing documentary films). While all these 42 students were requested to sit for pre-tests and post-tests, only students in experimental group answered the questions concerning the difficulties when dubbing films. The results reveal that there was a significant enhancement of the students’ performance in pronouncing skill in the aspect of sound linkage after applying dubbing documentary films activities. Moreover, students’ feedback on the use of the method is generally positive, and suggestions for reducing the obstacles when dubbing documentary films are provided to enhance the utilization of the method more meaningfully and efficiently.