The new type of construction machinery is used for cleaning the mortar fell down from the ceiling to the newly completed architectural floors. This process is usually undertaken by manual labor, which is inefficient and slow. The working efficient of the dust cleaner can be ten times increase over that of a manual labor, its working capacity can be reached of 1,000sq. M per day. The new desine of the intert type blade can be changed easily if one of the blade was worn, no need to change the whole brush disc, that is very economical for user.