Phenethyl acetate has flavour characteristic of rose, honey and apple, etc., and is an important flavour substance of sauce-aroma Baijiu. The screening and fermentation application of high-yielding phenethyl acetate yeast is important for improving the flavour and quality of sauce-aroma Baijiu. In this study, a strain of Pichia kudriavzevii X-8 with relatively high yield of phenethyl acetate was screened from the fermented grains samples of the brewing process of sauce-aroma Baijiu and applied to simulated fermentation experiments. The results showed that 66 and 72 volatile compounds were present in group A (without strain P. kudriavzevii X-8) and group B (with strain P. kudriavzevii X-8), respectively. The types and contents of esters, alcohols, acids and other flavor substances in group B were higher than those in group A. After 30d of fermentation, the content of phenethyl acetate in group B (0.214μg/g) was approximately twice that of group A (0.121μg/g). The dominant genera in group B were Weissella and Pichia, and there were also differences in the abundance of Lactobacillus and Pediococcus, Saccharomycopsis and Saccharomyces in the two groups. The addition of Pichia kudriavzevii X-8 had little effect on the physicochemical properties of the fermented grains, but enhanced the correlation of water content, acidity and flavour substances with fungal microorganisms, and increased the content of phenylethyl acetate and other important flavour substances. The results of the study were aimed to provide theoretical references for the quality improvement of sauce-aroma Baijiu and the practical application of functional strains in sauce-aroma Baijiu.