Abstract: Vocabulary is the foundation of all language skills. Learning a language means to study its vocabulary. The process of learning English is actually a process of enlarging and improving vocabulary. The paper explored the issue of how to enlarge and improve our vocabulary from word structure, memory method, and word's additional meaning perspectives respectively. It is concluded that learning by fine repetition from the perspective of sematic meaning of word is the best way to improve the memory efficiency and memory effectivenss. Moreover, correctly discerning words can raise our ability to use and understand the language.