Abstract: To illuminate function of yeast on the fermentation-layering of tea-seed-water-milk ( TSWM) , a strain of yeast ( NO.JJZ9911) was isolated and purified from 5 h-fermented TSWM.By mean of morphological observation, ITS r DNA and ( 26 S r DNA gene sequencing and comparison, and building and analysis of a phylogenetic tree, it was determined that JJZ9911 was one strain of Meyerozyma caribbica. Therefore the strain was named as tea seed yeast ( Meyerozyma caribbica JJZ11) , and its preservation number was CCTCC M 2016470.In the fermentation-layering process of TSWM, the number of tea seed yeast in fermented liquid gradually reduced with the extension of fermentation time and reduced to zero when fermentation reached to10 h. The p H of fermented liquor gradually reduced from 6.2 to 3.73 till fermentation reached to 10 h.The number of tea seed yeast colony was zero while the medium p H was less than 4.3.The fermentation-layering process of TSWM was synchronic with the number change of tea seed yeast, therefore, the tea seed yeast was one of the main microbial that caused fermentation-layering of TSWM.