The invention relates to a 3D printer. The 3D printer comprises an installation frame, an extrusion device, a displacement device, a discharge device and a processing platform. The discharge device comprises a wire outlet installation base, an upper wire outlet pipeline, a lower wire outlet pipeline, a wire outlet motor, a wire outlet driving wheel and a wire outlet auxiliary wheel. A wire conveying cavity is formed by the peripheral face of the wire outlet driving wheel and the peripheral face of the wire outlet auxiliary wheel. The wire outlet auxiliary wheel is in running fit with the wire outlet installation base. The wire outlet motor drives the wire outlet driving wheel to rotate. The upper wire outlet pipeline and the lower wire outlet pipeline are used for allowing printing materials to penetrate and are vertically and sequentially arranged on the wire outlet installation base. A wire conveying partition is arranged between the upper wire outlet pipeline and the lower wire outlet pipeline. The position of the wire conveying partition corresponds to the position of the wire conveying cavity. A swing arm is arranged on the wire outlet installation base. An adjustment bolt is arranged on the swing arm in the swinging direction. An adjustment nut limited to the end face of the other end, relative to the swing arm, of the wire outlet installation base and a limiting clamping ring limited to the end face of the other end, relative to the wire outlet installation base, of the swing arm are arranged on the adjustment bolt. Due to the adoption of the scheme, the 3D printer which is stable in printing material discharge is provided.