A quantitative analysis and feature extraction approach based on independent component analysis(ICA) is proposed to analyze the complicated nonlinear fluorescent spectra induced by nonlinear interactions of femto-second(fs) laser pulses with compound gas medium through which the laser pulses transmit.The spectra of different impurity concentration predicted by using the extracted features show a low error compared with the experimental values.The results of a quantitative analysis for the impurity concentration of twenty-seven sets of spectra data are satisfying.