A new research for authentic grape juice adulteration identification using elemental analysis-isotope ratio mass spectrometry(EA-IRMS) was developed.The carbon isotope ratio values(δ13C values) for 152 grape samples from different production regions were collected to primarily construct the isotopic database of authentic grape juices.The results indicated that the δ13C values of sugar and organic acid were in the ranges of -26.92‰-24.16‰ and-27.56‰-24.99‰，respectively.Based on the above δ13C values collected,the δ13C value limit for the authentic grape juice was proposed:the δ13C difference between organic acid and sugar Δδ13CO-S should be from-1.63‰ to 0.72‰.According to the above criteria,among 85 commercial samples,31 samples were confirmed adulterated with C-4 plant sugar or organic acid.According to the syrup addition test,EA-IEMS method could identify over 8%C-4 plant sugar adulteration.The newly developed method represented a significant potential application in the quality assurance of grape juice.