In this paper,a method was established for rapid determination of total polysaccharides in Pteridium aquilinum.The real contents of total polysaccharides in 140 P. aquilinum samples were determined by the anthrone-sulphuric acid method.A rapid quantitative model for the contents of total polysaccharides in the P. aquilinum samples was established by fourier transform mid infrared spectroscopy (FTIR) combined with partial least square method (PLS).Eight different spectral preprocessing methods (multiplicative scattering correction,standard normal variate,first derivative,second derivative,first derivative combined with standard normal variate method,first derivative combined with multiplicative scattering correction method,second derivative combined with standard normal variate method and second derivative combined with multiplicative scattering correction method) were compared and the characteristic FTIR signals of polysaccharides were utilized as selection modeling bands,which were used to optimize the predicting model.The results showed that when the selected ranges for the model were 1 750-1 600,1 500-1 400,1 350-1 290,1 160-1 070,1 060-970,930-800 cm^-1 and the standard normal transformation method was used as the preprocessing method,the correlation coefficient R² of the calibration set was 0.930 8,the calibration mean square error (RMSEC) value was 0.374%,the correlation coefficient R² of the test set was 0.914 5 and the mean square error of prediction (RMSEP) value was 0.418%.The error of complete external validation of 20 samples was -0.35%-0.31% and the relative error of complete external validation was -0.83%-5.24%.The established quantitative model could be used to predict the contents of total polysaccharides in P. aquilinum.