Nowadays, a majority of countries in the world speak English which is one of the most important languages for international communication. It becomes a second language in all universities, in all grades. However, it is not easy to learn a foreign language well. English majors at HaiPhong Private University are taught four skills of listening, writing, reading and speaking from the first term. Of the four skills, many students consider writing the most difficult because it requires the knowledge and professional use of grammar and vocabulary to write a paragraph as well as a complete essay. Writing is different from spoken language. In spoken language, we use many unfinished sentences, ungrammatical structures. However, written language requires formal vocabulary, correct spelling and grammar structure as well as well organized sentences and ideas. Moreover, writing uses letters and punctuation under rules of grammar.