The invention discloses a 3D printer wire feeding structure. The 3D printer wire feeding structure comprises a fixed base; the fixed base is connected with a wire feeding motor; a cavity is formed in middle of the fixed base; a wire feeding driving wheel is arranged on one side in the cavity, and a driven wheel structure is arranged on the other side in the cavity; the driving wheel is connected with a driving wheel shaft; the driving wheel shaft is supported on the inner wall of the cavity of the fixed base through a bearing; the driven wheel is connected with a driven wheel shaft; a printing wire channel is formed in the fixed base in the perpendicular direction; the driven wheel shaft is connected with a driven wheel shaft horizontal position adjusting structure; and the driving wheel is matched with the driven wheel to convey printing wires to a printing head part. The 3D printer wire feeding structure is simple and compact in structure, is convenient for disassembly, replacement and maintenance, can conveniently and precisely adjust a shaft distance between the driving wheel and the driven wheel through the horizontal position adjusting structure, and can reliably convey the printing wire materials to a melting position of the printing head part for timely melting to satisfy the printing requirements.