He has been engaged in fieldwork-based study of Tibeto-Burman languages over the past 15 years since his doctoral work on Prinmi, a minority language of southwestern China. His research interests center around languages of China (especially the Sinitic and Tibeto-Burman) and extend to those with typological similarities with Chinese languages, particularly on the tone system. He has also developed a deep concern about the well-being of minority languages through descriptive work conducted in China and has studied issues related to language endangerment.