The oxygen isotope ratios 17O/16O and 18O/16O in Venus׳s atmosphere were measured simultaneously by ground-based IR spectroscopy. The CO2 absorption lines in the 2648 cm−1 (for 17O/18O) and 4582 cm−1 (for 18O/16O) regions were observed using the IRTF/CSHELL spectrometer. The deviations of the isotope fractions are found to be δ17O=+92±158‰ and δ18O=−42±85‰ as compared to the terrestrial standard (HITRAN 2012) where the uncertainties include both random and systematic errors. Such combination agrees with the Earth–Moon fractionation line within the errors. This is consistent to the fact that the proto-Venus matter was also well mixed with the proto-Earth–Moon matter.