Language is a complicated system, which mainly contains phonology, vocabulary, grammar. The vocabulary is just like stocks used to build the house of a language. Lexicon is fundamental material in language learning. The author attempts to explore English word formation form morphemes. The morpheme, can be considered as "the smallest functioning unit in the composition of words". Morphemes are classified into prefix, root and suffix. In order to have a good command of words, English learners could adopt the rules of word formation from morphemes to enlarge vocabulary efficiently.