Abstract: The lignin contents of plantation poplar were estimated using the method of the near infrared. The lignin contents of 42 samples of poplar were determined by national standard of China, and then the near infrared(NIR)of all samples were collected by LabSpec Pro FR/A114260 in this paper. The calibration and validation model were built using PLS1, PLS2 and PCR with different pretreatment methods of no-pretreatment. Baseline, the first derivative and the second derivative in different spectral region of 350-2 500 nm, 1 300-2 050 nm and 2 050-2 500 nm. The result shows that the model is the best using PLS2 with no-pretreated of spectral data and 10 principal components in 1 300-2 050 nm. The coefficients of correlation(r), the root mean square error and the standard error of calibration model are 0.968 5, 0.006 4 and 0.006 6, respectively, and 0.655 3, 0.020 2 and 0.020 5 for validation model. The correlation(r)is 0.766 5 between the prediction and lab measuring values of the samples without involved in modeling.