Abstract: For online measuring the filling value of cut strips in tobacco primary processing line, an online measuring system working on the instantaneous mass signal from an electronic belt weigher was designed, for this purpose, the feeding unit was modified to keep cut strips under fixed pressure and provide a constant test volume. The accuracy and stability of the measuring system were validated. The results showed that: 1) for the cut strips of the same brand, there existed a linear correlation (R²=0.960) between the filling value and instantaneous mass reading of the electronic belt weigher, and the regression model reached a significant level (P<0.001); 2) for the cut strips of 6 batches with different filling values, there was no significant difference (P>0.05) of filling value between the online and offline measurements, the absolute and relative errors between the two were 0.03 cm³/g and 0.56%, respectively. It proved that the designed system was accurate, stable and suitable for the online measurement of cut strips' filling value.