Effect of high gravity factor, gas flow rate, and liquid flow rate on dust removal efficiency of a rotating packed bed (RPB) was investigated at dust concentration as low as 200 mg/m3, in which coal-fired fly ash and RPB were used as experimental dust and dust removal equipment, respectively. The grade collection efficiency of the RPB was carried out and the concentration range of dust that removed effeciently by RPB was explored at dust concentration lower than 200 mg/m3. Results show that, at conditions that high gravity factor of 163, gas flow rate of 400 m3/h, and liquid flow rate of 0.5 m3/h, dust removal efficiency is as high as 93.18% for a 200 mg/m3 inlet dust concentration. Grade collection efficiency curves show that the cut size of a RPB is about 0.08 μm, dust removal efficiency for particle size of 2.5 μm is approximately 95%?99.75%. Dust removal efficiency is 81.25% with inlet dust concentration of 30 mg/m3.