The invention relates to a method for processing microscale dust in tail gas of a calcium carbide furnace. A depth dusting system in the tail gas of the calcium carbide furnace purification process comprises a compressor, a buffer tank, a wet type dust collector, a gas-liquid separator and a filter, which are connected with one another sequentially; after being subjected to pressure increase by the compress, the tail gas including dust passes the buffer tank, then enters the wet type dust collector for dusting, and comes out the wet type dust collector to be a tail gas gas-liquid mixture of the calcium carbide furnace; the tail gas gas-liquid mixture is subjected to separation of droplets in dust by the gas-liquid separator, and then passes the filter to remove fine droplets which are not separated, in the dust by filteration; and then the tail gas subjected to dust removal is output from the depth dusting system. The method solves the problems that pipeline and equipment have high probability of blocking which is caused by that a lot of dust with small particle graininess and viscosity is in tail gas of the calcium carbide furnace, the temperature is difficult to control, and potential safety hazard can not be avoided, has the advantages of less equipment, practicable process technology, safety and stability, can achieve the purpose of dusting of the tail gas of the calcium carbide furnace, energy conservation, emission reduction and environmental protection, and can be widely used in the tail gas dusting processing technology.