This study adopts Appraisal Theory to conduct a positive discourse analysis of moral values in primary school English textbooks widely used in China. The study finds that: 1) Overall, there are no moral values represented in Grade One. From Grade Two to Grade Four, there is one or two moral values. In Grade Five and Grade Six, there are four and three moral values respectively. Totally there are eight types of moral values, the content of which conforms to Piagetian Moral Stage Theory. 2) Judgment resources take the largest proportion in all values. And in judgment, social sanction outnumbers social esteem. Apart from the lack of appreciation resources in the value of animal protection, the seven values all include affect, appreciation and judgment. The findings may be helpful for researchers to better understand the characteristics of moral values representation in Chinese primary school English textbooks and provide suggestions for future teaching practices and textbook development.