The purpose of this study is to present some aspects of the sound system of Gān’gōu Chinese, a Northwest Mandarin variety of the Amdo Sprachbund, and to compare them with other Northwest Mandarin languages. The grammatical structure of Gān’gōu has been shown to exhibit an Altaic-type orientation (verb-final syntax, case system etcetera), while the phonology of Gān’gōu, which has only recently been examined, is of a Sinitic type. The questions asked are, how has the phonology of Gān’gōu changed as compared to its ancestor Old Mandarin on the one hand and Mandarin languages outside the Amdo Sprachbund on the other? How is it similar to other Northwest Mandarin varieties and where does it possibly differ? It has been found that Gān’gōu shows significant phonological similarities with the other members of the Northwest Mandarin branch. Also, many of the phonological innovations in Gān’gōu seem to be typical of the languages of the Amdo Sprachbund as a whole, further establishing the position of Gān’gōu as a member of the Sprachbund. Eight innovations are discussed, seven related to retentions or losses in the medial or coda part of the syllable, one related to tone reduction. After an overview of the syllable structure and phonemic inventory of Gān’gōu, these innovations are presented in turn.