Abstract: In order to rapidly determine ibuprofen in ibuprofen sustained-release capsules, the work as mentioned by the article was carried out. High performance liquid chromatography (HPLC) was used as reference, and Raman spectrometer was used to scan 5 calibration set samples and ibuprofen reference substance. The original Raman spectra were imported into the computing platform, with waveband in the range of 250-1 800 cm^-1. The fluorescence photo-bleaching difference approach method was used for baseline correction, and the second order filter derivative was used for noise supression. The variance values of angle cosine between Raman spectra of each sample and ibuprofen reference substance were calculated by vector angle conversion algorithm, and the correlation equation of the model was obtained by fitting the variance values to mass fractions of ibuprofen. The model was used to predict content of ibuprofen by collecting Raman spectra of the test samples. As shown by the results, linear relationship between mass fraction of ibuprofen and its variance value of angle cosine was kept in the range of 55%-90%, and the relative deviations of validation set samples between the predicted values and the reference values obtained by HPLC was in the range of 3.0%-3.8%. The model has been used for substantial samples, with the relative deviations between the predicted values and the reference values in the range of 1.2%-6.8%, and RSD (n=5) of the predicted values were ranged from 0.99% to 3.1%.