Adulteration of walnut oil could be detected accurately and rapidly using FTIR or fluorescence spectroscopy in combination with chemometrics. The determining limit of soybean oil adulterated in walnut oil was 10% by FTIR spectroscopy, and fluorescence spectroscopy has a high sensitivity with a determination limit of less than 5%. Fluorescence spectroscopy is therefore more applicable than FTIR spectroscopy in the quantitative determination of walnut oil adulteration.