The fresh, dried chestnut rose (CR) (Rosa roxburghii Tratt) and stored for several days wild CR pulp were analyzed by using the infrared spectral technology of Fourier transform infrared spectrometer (FTIR) at room temperature in this paper. To compare the spectral characteristics of fresh and dried CR pulp, we extracted their flavonoids by the ultrasonic-assisted solvent extraction (UASE) method and ultrasonic combined enzyme-assisted semi-bionic (UCES) method, respectively. Moreover, absolute ethanol was used to extract CR flavonoids in the UASE method for the extraction of CR flavonoids. And then Pepsin, tryps in and bile were used to simulate the environment of enzyme assisted gastrointestinal digestion for the extraction of Flavonoids from Rosa roxburghii Tratt. The Fresh pulp and Dried pulp were respectively reacted for 0, 0.5, 1, 1.5, 2 and 2.5 h in the two extraction methods. First of all, the infrared spectra data of fresh pulp and dried pulp were measured. Then, by comparing the optimal characteristic wavelength combination of the two methods for extracting CR flavonoids, we found that under the same reaction conditions, when the reaction time is at 1.5 h, the transmittance intensities of the infrared spectrum from the fresh CR and the dried CR in the UASE method were 83.5% and 84%, respectively; in the UCES method, their transmittance intensities were 32% and 38%, respectively. Therefore, combined with Lambert-Beer’s law, when the reaction time was the same, the UCES method was superior to the UASE method for extracting CR flavonoids. Besides, with the increase of reaction time, the infrared absorption peak intensity of the two extraction methods showed an upward trend. After being reacted for 2 h, the absorption peak was gradually stable. The results showed that the infrared absorption peaks at 3 419 cm^-1 (hydroxyl group O—H stretching vibration), 1 615 cm^-1 (Carbonyl C＝O bond stretching vibration) and 1 053 cm^-1 (alkyl group) of the CR flavonoids could be distinguished. The infrared absorption peaks of flavonoids in fresh pulp and stored at room temperature for several days were consistent with that of quercet in and kaempferol. Under the same experimental conditions, the flavonoids concentration of dried CR was higher than that of fresh CR pulp. This research can provide references for identifying the production of functional medicines and foods of chestnut rose.