Printing head of 3D printer

The utility model provides a printing head of a 3D printer and solves the defects of complex structure, easiness in blocking and leaking materials and poor cooling effect of a printing head of the 3D printer in the prior art. The printing head comprises an extruding part, a ventilating part, a heating part and a wire outlet part, wherein the wire outlet part comprises a fixed seat and a line bank arranged at the rear end of the fixed seat; the extruding part, the ventilating part and the heating part are mounted on the fixed seat. The printing head has the beneficial effects that by utilizing internal exhausting type axial fan as well as a stepping motor for ventilating the air blown by the axial fan to the extruding part, the temperature of the stepping motor is decreased, the normal working of the stepping motor is guaranteed, and the service life of the stepping motor is prolonged; meanwhile, the downward airflow plays a direct cooling role in a printing process of the printing head of the 3D printer, so that the use of two fans is omitted; by designing a ventilating channel, the volume and weight of the printing head are effectively reduced.