The drum Counting system was calibrated in this study. For (CS)-C-137, the counting efficiencies were around 14-1% when the density of the waste of the drum was changed from 0.15 to 2.3g cm(-3). The effects of the background, hot spot, system linearity, sample density and weighing were also evaluated in this work. The combined standard uncertainty of the drum counting system for the Cs-137 in the density of 1 g cm(-3) was around 12%. To verify the counting system, the drums containing radioactive solution were prepared by the NMI as the blind samples. A discrepancy below 15% was shown between the counting results and the reference values of the NMI.