Medical English is relatively more difficult than general English,especially its vocabulary.Those medical English words are long and complex,making it hard to remember.But medical English vocabulary has its own features,which would help us in learning vocabulary.On the basis of many medical English materials,the paper explores the features of etymology,affixes and roots of medical English. Medical English is relatively more difficult than general English, especially its vocabulary.Those medical English words are long and complex, making it hard to remember.But medical English vocabulary has its own features, which would help us in learning vocabulary.On the basis of many medical English materials, the paper explores the features of etymology, affixes and roots of medical English.