Abstract: 【In order to determine the mixing ratio of microwave expanded stems(the cut stem prepared by microwave expanded and recutting technology) in cigarette and evaluate the mixing uniformity of it in cigarette. The cut tobacco of cigarette for brand A of three class was taken as background. The microwave expanded stems and cut tobacco (three class of A cigarette brand) were mixed with different ratios (0%-50%) and the NIRS (near infrared spectrum) were collected. The prediction model of NIRS was established by partial least square. The mixing ratio of microwave expanded stems in cigarette and in each part (each cigarette without filter was cut three equal sections) of cigarette were detected, respectively. The deviation of the mixing ratio of microwave expanded stems in cigarette and in each part of cigarette was calculated. And the mixing uniformity of microwave expanded stems in cigarette was also evaluated according to the deviation. The correlation coefficient of the model was 0.9986, the model had high forecast accuracy (RADP=1.72%) and good reproducibility (RSD<3%).So this model could be applied to fast determine mixing ratio of microwave expanded stems in cigarette for brand A of three class. The deviation of mixing uniformity for microwave expanded stems in cigarette and in each part of cigarette was less than2%.So the NIRS method could be applied to fast determine the mixing ratio of microwave expanded stems in cigarette and evaluate the mixing uniformity for microwave expanded stems in cigarette; The evaluation result indicated that the cut stem prepared by microwave expanded and recutting technology had fine mixing uniformity in cigarette.