In order to study osmotolerant yeasts which are capable of causing spoilage for apple juice concentrate, the yeasts present in apple juice concentrate collected from apple juice processing plants in Shaanxi Province were isolated and purified by using osmotic YPD media. The sugar-tolerance of different yeast isolates was assayed. The colony morphology, cell morphology and physiological characteristics were studied and the phylogenetic tree based on 26S rDNA sequence analysis was constructed to determine the genetic location of isolates. Except the isolate N18 which was identified as strain of Candida tropicalis, all the other isolates belonged to Zygosaccharomyces rouxii. All the isolated strains of Z. rouxii were capable of growing in 900g/L glucose and apple juice concentrate, displaying better sugartolerance ability and greater harm to the quality of apple juice concentrate than isolate of C. tropicalis which showed sugar-tolerance of 750g/L glucose and no visible growth in apple juice concentrate. The results suggested that strains of Z. rouxii might pose a threat to the quality of apple juice concentrate, and it was needed to be controlled in the production line of apple juice concentrate．