Preparation of sourdough using Tibet kefir milk to investigate changes in microbial diversity during the passing of Tibet kefir milk sourdough. Illumina Miseq sequencing was utilized to detect microbial community composition as well as changes in the Tibet kefir milk and sourdough during the passaging process. The results show that: Ascomycota， unclassified_k_Fungi， Rozellomycota， Proteobacteria， Firmicutes， Chloroflexi are the dominant bacteria in Tibet kefir milk and Sour dough， Rozellomycota， Acinetobacter are the dominant bacteria in fermented milk and sour dough， Pediococcus， Saccharomyces is a unique dominant bacterium in sourdough. The sourdough was still able to maintain the same microbial community composition as the previous generations in the 4th generation， and the microbial diversity decreased sharply in the 6th generation， indicating that the preparation of Tibet kefir milk was able to stably pass on for 4 generations in sourdough， and has the potential to be a leavening agent applied to sourdough making. This study can provide a theoretical basis for the development of leavening agent products for traditional flour products in China.