English as an international language has become basic tools to learn,meanwhile new words update daily,therefore, there are too much vocabulary for foreigners to remember. So we often hear students complain that they often meet new words but they do not know whether they should look up all words in the dictionary and they spend a lot of time memorizing vocabulary but still get nowhere. Therefore how to enlarge our vocabulary is one of the most headache problems for students. Gradually, they lose interest to learn English,or even hate the subject.It is urgent for our teachers to solve the problem- expanding students’ vocabulary. Enlarging vocabulary not only means helping students remember new words but also means students can really know how to use them in real life,which ignored by a majority of teachers. In order to help students, different methods are used by teachers around the world. This essay argues what kinds of words and the size of words do students need to learn,what methods can English teachers in China use to present new words to their students,and how to train students themselves to learn English vocabulary.