The invention belongs to the technical field of filtering devices and particularly relates to a dust filtering device which comprises an air inlet, a bending pipe, an air outlet and a filtering mechanism. An outlet at the short end of the bending pipe is the air inlet, an outlet at the long end of the bending pipe is the air outlet, and the filtering mechanism is arranged at the short end of the bending pipe. An activated carbon filtering screen is arranged in the air outlet. By means of unitization of the filtering mechanism of the filtering device, disassembly and washing of the filtering screen can be slightly achieved. A first filtering screen and the second filtering screen are fixed on the support frame by arranging the support frame in the filtering mechanism, and the filtering screen is not easy to deform. A single filtering screen is changed into a double-layer filtering screen structure with the first filtering screen and the second filtering screen, and filtering effect is better. The dust filtering device achieves the effect of secondary filtering by arranging the activated carbon filtering screen at the air outlet.