The present application provides a filament spool holder for a 3D printer, a 3D printer, and a 3D printing system. The filament spool holder comprises: a filament spool holder body; at least two filament cylinder rotating shafts, connected to the filament spool holder body, wherein each of the filament cylinder rotating shafts is configured to hold one 3D printing filament spool; and a drive assembly, wherein the drive assembly is configured to drive a first filament cylinder rotating shaft of the at least two filament cylinder rotating shafts to rotate, thereby enabling the first filament cylinder rotating shaft to drive the 3D printing filament spool held on the first filament cylinder rotating shaft to rotate.