The invention describes a dust-cleaning technique using wetting method of organic chlorosiline gas. The synthetical gas from double cyclone enters inside from the bottom of washing tower, the discharged liquid from the kettle enters in flash pot, evaporated gas enters in flash condenser, non-condensing gas is entirely discharged after washed by washing tower, condensed liquid enters in liquid-recovery tank and residue is discharged into residual tank. The gas on the top enters in precooling device on top of the tower, after gas-phase is deeply cooled, non-condensing gas goes to chlorine methane buffering pot, condensed liquid enters in rough monomer medium pot, part of which returns to the tower and part of discharging is sent to rough monomer tower for processing.