The objective of this study is to describe the implementation of using animation video and to identify the problem faced in the implementation of using animation video in teaching English vocabulary at the fourth grade. The research was conducted at MI Zumrotul Wildan Ngabul, the number of the students are 23. The researcher used descriptive study during the research. In collecting the data, the researcher uses classroom observation and interview. The researcher conducted classroom observation about three meetings; in every meeting the students got new vocabularies from English animation video. In every meeting the teacher gave task to the students. The researcher analyzes the score using mean of each task to find out the improvements of students’ vocabulary mastery using animation video. In the classroom observation, it could be seen that there were many new vocabularies that could be learned through watching the animation video. The students could master their vocabulary in three animation videos that had been played by the teacher. The students knew the meaning of new vocabulary, the students could mention the vocabulary based on the categories and the students could correct the action verbs with the animal based on the animation video. The researcher conducted interviews after classroom observation, the researcher interview the teacher and some of students. The data which was collected by using interview also showed that using animation video had strength and weakness. The strength of the animation video was inviting the students’ attention. The students did not felt bore, it also saved time and effort. The weakness of the animation video was some of passive students just interested with the picture only, did not understand about the vocabulary and the pronunciation. By using animation video in teaching vocabulary, students could understand and memorize new vocabulary easily. The students also could involve and participate actively during the lesson. It is suggested that using animation video in teaching English vocabulary can be recommended for the English teachers. The mean score had the advancement from three meetings. In the first meeting the students got 93.04, while in the second meeting they got 87.39, and in the third meeting they got 95.21. In this research, the researcher finds the students were not getting bored and more enthusiastic during teaching learning process, when the teacher used animation video.