The invention discloses a 3D composite material printer. Printed pieces which make users satisfied are obtained. According to the technical scheme of the 3D composite material printer, the 3D composite material printer comprises a spray nozzle part, a drive part, a machine body and a control part; the spray nozzle part sprays a composite material; the drive part comprises an X-direction drive stepping motor, a Y-direction drive stepping motor, a Z-direction drive stepping motor and a corresponding transmission device; X-direction movement, Y-direction movement and Z-direction movement which are required by the 3D composite material printer are achieved; the machine body supports the 3D composite material printer; and the control part controls operation of the 3D composite material printer. A commercial plastic wire material is used as a main material, the users can freely add auxiliary materials (such as particles, fiber, slurry and dye), and therefore personalized modification, including color changing, of the materials can be conveniently achieved, and the printed pieces with the performance capable of making the users satisfied are obtained.