In this study,the model for determination of amino nitrogen concentration in cottonseed meal hydrolysate was developed by near infrared spectroscopy.The near infrared measurements of samples were analyzed by partial least-squares( PLS) regression with selecting different wavelength and spectral pre-processing methods.The parameters of optimized model as followed: wavelength was 1300-1800nm,spectral pre-processing methods was first derivative + straight line subtraction.The root mean square error of cross validation was 0.457 g/L; the determination coefficients were 0.927 2; the residual predictive deviation was 3.71.Compared with predict value and actual measured value of external validation set,determination coefficients was 0.944 5 and the average relative errors were 5.05%.These results showed that prediction model could predict amino nitrogen concentration in cottonseed meal hydrolysate accurately and quickly,and it would provide theoretical basis for the control the quality of cottonseed meal hydrolysate.