Reading is an important skill in learning English. However, reading class is not emphasized in some primary schools in China, and there are various problems with the reading activities, which inadequately just focus on teaching of words, sentences separately from texts. This paper aims to bring out a whole system of principles in designing flexible English reading activities to help students form a good reading habit, apply reading skills, use language learned pragmatically and be familiar with the cultures covered in read materials. At last, some examples are offered to demonstrate how to implement these principles so as to enhance reading for Primary school students effectively.