Lacquerware is an important part of Chinese tangible cultural heritage, which runs through the whole Chinese history. In order to improve the performance of raw lacquer, ancient people mixed drying oil with raw lacquer.The proportion ofdrying oil directly affected the propertiesof the lacquer film. Unfortunately, due to the lack of relevant historical literature and the aging degradation of ancient lacquerwares from archaeological excavations, it is difficult to determine the materials used in the lacquer film quantitatively. Therefore, in order to understand the ratio of drying oil to raw lacquer usedin the ancient lacquer making process, it is necessary to establish a method for quantitative analysis of the ancient lacquer film oil/lacquer ratio. In this study, the ancient lacquer film was quantitatively analyzed by FTIR-ATR and NIR through standard samples. The results showed that FTIR-ATR could not achieve the purpose of quantitative analysis when the lacquer film seriously aged. The PLS model established by near-infrared spectroscopy combined with chemometrics could quickly and non-destructively analyze the oil/raw lacquer ratio of ancient lacquer film. The results show that the PLS model has good stability and predictability, with lower the root mean square error of calibration (RMSEC), root means square error of prediction (RMSEP), root mean square error of cross-validation (RMSECV), and correlation coefficients of Rc, Rp, Rv above 0.99. The method was applied to analyze ancient lacquerwares. The relative content of the drying oil contained in the ancient lacquer film was calculated by the PLS quantitative model, and the different proportions of oil/rawlacquer used in lacquer making in different times and regions were determined. It provides a scientific basis for interpreting the "oil and lacquer" technology of ancient China and provides scientific support for the conservation and restoration of lacquer artifacts.