The quantitative calibration models of three polymorphs α-CL-20、γ-CL-20、ε-CL-20 in ε-CL-20 product were established by mid-infrared diffuse reflectance spectroscopy combined with partial least squares( PLS) method of chemometrics,and the cross-validation and external validation to the models were performed. Results show that three models have high accuracy and precision,the determination coefficients of cross-validation( R~2) are 0. 9973,0. 9714,0. 9848,respectively,and the root mean square error of cross-v...