The invention discloses a 3D printer, and relates to the technical field of 3D printing. The 3D printer comprises a machine body, a working table, a lifting device and a spray head device; the working platform, the lifting device and the spray head device are arranged in the machine body, the working table is connected with the lifting device, the lifting device is a device combining two ball screw devices, the ball screw devices are arranged at the two sides of the working table, and each ball screw device comprises a lifting motor, a screw rod, a guide rail and a sliding block, wherein the lifting motor is connected with the screw rod which is arranged in the guide rail, and the sliding block is connected with the screw rod; the spray head device comprises a spray head, a connecting arm, a rotating shaft, a motor, a support table and a mobile table, the spray head is connected with the connecting arm which is fixedly connected with the rotating shaft, the rotating shaft is connected with the motor which is fixed into the support table, and the support table is fixedly connected with the mobile table. The 3D printer is simple in structure, convenient to operate, capable of automatically monitoring changes of printing materials and high in printing precision.