Abstract: Near infrared spectroscopy analysis of the inner quality of agricultural products was a rapid and accurate technique. The effects of sample handling, chemical analysis as well as data processing methods were investigated with regards to the performance of the near infrared spectroscopy technology in determination of inner quality of agricultural products. The analyzed parameters were: 1)range of samples for calibration; 2)physical and chemical properties of samples; 3)errors relating to chemical analysis; 4)fluctuations in apparatus and circumstances; 5)pretreatment methods for NIR spectrum; 6) chemometric methods for calibration and validation analysis. In order to obtain reliable results, it was advisable to take these variables into consideration when establishing NIR models for estimate the ingredients of agricultural products.