In this study, fresh peach juice is taken as the research object, and the moisture in the peach juice sample is extracted without fractionation by using the full-automatic vacuum condensation extraction technology. The hydrogen and oxygen isotopes in the water sample are simultaneously determined by using the element analyzer-stable isotope mass spectrometer (EA-IRMS). The reliability of the analysis method is evaluated by adding tests, and the change rule of hydrogen and oxygen isotope ratio after the peach juice is mixed with different proportions of moisture is discussed by using the established analysis method and multiple comparative analysis. The results showed that the measured values of the added samples were as follows: δ ²H=( 11.10±1.39)‰ and δ ¹⁸O=( 2.38±0.53)‰ in the added USGS45 samples respectively. Adding δ ²H=( 62.50±0.59)‰ and δ ¹⁸O=( 7.95±0.41)‰ in GB04459 sample; Adding δ ²H=( 142.00±3.40)‰ and δ ¹⁸O=( 20.26±2.14)‰ in GB04460 samples, compared with standard water samples USGS45, GB04459 and GB04460, the hydrogen and oxygen isotope ratios of the three samples have no significant difference (P＞0.05), indicating that no obvious hydrogen and oxygen isotope fractionation effect occurred during the operation of this method. The hydrogen and oxygen isotopes in freshly squeezed peach juice are obviously depleted in heavy isotopes after being doped with exogenous groundwater. Combining these two indexes, it is shown that the identification of mixing water in peach juice can be realized from 10% of groundwater.