The present invention provides a residue removing device for removing residues in a partition plate, and a related 3D printer for use on a working platform. The partition plate e.g. of a 3D printer has a plurality of openings arranged in an array, and residues may be filled in the openings. The residue removing device includes a base plate and a plurality of jutting pins disposed on an upper side of the base plate. The jutting pins are arranged in an array corresponding to the openings array such that the jutting pins are capable of being inserted into the openings, in order to easily remove the residues in the openings of the partition plate.