The invention discloses an ultrafine particle mixing device. An ultrafine particle mixing device system comprises a hopper, a spiral feeder, a Roots blower, an air chamber, a circulating fluidized bed, a cyclone dust collector, a vertical pipe, a material returning device, a bag-type dust collector and a material collector, wherein the circulating fluidized bed comprises a low speed bed, a transitional section and a high speed bed; a porous plate is arranged at the upper part of the air chamber as an air distribution plate; and the bag-type dust collector is connected with the cyclone dust collector. Ultrafine particles and auxiliary fluidized particles are available in the low speed bed. The auxiliary fluidized particles are added to the low speed bed through an auxiliary fluidized particle storage bin. The number of the types of the ultrafine particles is not less than two. The particle sizes of the ultrafine particles are less than 100 microns. The Roots blower supplies inert fluidizing gas which does not react with the ultrafine particles. The particle sizes of the auxiliary fluidized particles are more than 100 microns and less than 100 mm. A feeding device is the spiral feeder.