Both books are very good. He Ziran, Ran Yongping and He are all important scholars in pragmatics. If possible, both books should be listed as reference books. Look at them all, which will help you write more articles. On the other hand, don't write too many papers and reference books. It's best to collect all the important documents related to your topic as much as possible. In addition to these two monographs, try to find some periodical papers and look for them on China Knowledge Network. You should be able to find an article that suits you.
If you must give up one book and choose only one, then choose A New Introduction to Pragmatics by He Ziran and Ran Yongping, because this book is newer. Moreover, He Ziran and Ran Yongping have made more achievements in pragmatics. In addition, He Ziran is the editor-in-chief of the first pragmatics textbook in China, which has a greater influence.