The Norman Conquest of England in 1066 had a great influence not only on the country,but also on the English language.This article briefly introduced the successional development of English in Middle Ages from those three aspects including pronunciation,vocabulary, and grammar. The Norman Conquest of England in 1066 had a great influence not only on the country, but also on the English language. This article briefly introduced the successional development of English in Middle Ages from those three aspects including pronunciation, vocabulary, and grammar.