Corn stover contains abundant nutrients for animals and it is the main source of roughage for large domestic animals. To guarantee the quality of feed, the online measurement of the nutrient content of corn stover is essential when it is being used as a roughage feed or a raw material for silage. In the present study, the online determination of moisture, crude protein (CP), acid detergent fiber (ADF) and watersoluble carbohydrate (WSC) of corn stover was investigated using near infrared spectroscopy (NIRS) operating over a conveyor belt moving at 20cm/s. The distance between the sample surface and the scanning window was 100mm. The 217 corn stover samples, collected from three provinces of China, were crushed to not more than 5cm for spectral analysis. The relative standard deviation (RSD) and ratio of standard error of performance to standard deviation (RPD) of the models developed for moisture, CP, ADF and WSC were 9.03% and 1.97, 11.36% and 2.31, 3.75% and 2.02 and 16.18% and 3.61, respectively. The results showed that it was feasible to determine the moisture, CP, ADF and WSC contents of corn stover using on-line NIRS, which would help raise the efficiency of nutrient measurement and thus guarantee the quality of feed. The sensitive bands of the models were investigated, which could help to simplify the models and thus reduce the cost of the specific spectrometers for practical application.