In order to solve the serious dusting problem for soil thermal desorption device, the method of acoustic agglomeration combined spray was applied to the dust removal of the thermal desorption device. The effects of sound frequency, initial dust concentration, sound pressure level and spray flow rate on the dust removal efficiency (average particle size of dust less than 10 μm) were studied. The experimental results showed that under the condition of sound frequency of 1400 Hz and spray concentration of 1.0 L·m^-3, the dust removal efficiency of the agglomeration chamber reached 98% within 60 s. When the sound pressure level was increased from 145 dB to 153 dB, the dust removal efficiency is increased by 38%. SEM results showed that the particles were crushed and aggregated after acoustic wave treatment. Adding spray could improve the dust removal efficiency, but the effect of spray concentration on final dust removal efficiency was not significant. The optimal sound frequency after spraying was 1400 Hz. The higher initial concentration of dust and spray could lead to the higher dust removal rate and the final dust removal efficiency in the early stage of agglomeration. When the spray concentration was 2.0 L·m^-3, the dust removal efficiency was 44% higher than that without spray, indicating that the acoustic wave agglomeration had a better effect on the use of high concentration aerosol. The results of this paper could offer useful information in the investigation and development of dust removal technology of thermal desorption device.