Secondary cleaning system of peanut pickup machine, dust removal device and peanut pickup machine

The invention relates to a secondary cleaning system of a peanut pickup machine. The system comprises a vibrating screen (17), a first cleaning fan (18), a second cleaning fan (15) and a residue elevator (16), the vibrating screen is obliquely arranged at the lower part of a straw chopper (2) of the peanut pickup machine, and the head end of the lower part of the vibrating screen is provided with the first cleaning fan; and the second cleaning fan and the residue elevator are arranged at the tail end of the lower part of the vibrating screen, and an air outlet of the second cleaning fan is formed in the end part of the end, far away from the first cleaning fan, of the residue elevator. The invention further provides a dust removal device and the peanut pickup machine. The second cleaning fan is additionally arranged, so that the cleaning wind power is increased, straw and peanuts are prevented from falling into a residue auger, and the blockage of the whole cleaning system is avoided; and a water tank is addi