This research is about the influence of using duolingo application toward students’ English vocabulary knowledge of the eleventh grades in SMAN 1 Abung Kunang. With a main problem is students’ have limitations in mastering vocabulary in english and understanding of vocabulary. The aim of this research is to investigate the influence of using duolingo application toward students’ vocabulary knowledge. This research used an experimental method with a pre experimental type. The population in this study were eleventh grade students of SMAN 1 Abung Kunang with a total of 94 students. However, the sample used in this research was 63 students with class XI Natural Sciences 1 as the control class and XI Natural Sciences 2 as the experimental class. The experimental class was taught using the duolingo application as media, while the control class did not use the duolingo application. The instrument used in this research was 50 multiple choice test. Data collecting technique in this reasearch used post-test only. The data obtained was then tested using the t-test formula. Based on the results of t-test calculations with a significance level of 5%, it shows that tobserved = 5.42 is higher than ttable = 1.999. The results of this research show that the use of the Duolingo application has an significant influence on English vocabulary knowledge in the eleventh grade of SMAN 1 Abung Kunang. So the conclusion in this research is that there is an influence between using the duolingo application as a learning medium on students’ vocabulary Knowledge.