The invention discloses a 3D printer capable of being cleaned automatically. The 3D printer comprises a 3D printer main body, wherein a supporting plate is arranged in the 3D printer main body, a slide belt and an automatic cleaning device are arranged on the outer surface of one side of the supporting plate, a fan is arranged on the right side surface of the 3D printer main body, the fan is covered by a sealing cover, mutually symmetrical slide grooves are respectively arranged on the edges of the left side and the right side of the opening position of the right side surface of the 3D printermain body, the sealing cover is in slide fit connection with the 3D printer main body through the slide grooves, an air outlet is formed in the bottom of the left side of the 3D printer main body, and a dust removing box is arranged in the 3D printer main body. The 3D printer disclosed by the invention has the advantages of simple and reasonable structure and reasonable design; when the 3D printer is automatically cleaned, the action of the fan can guarantee that dust is effectively adsorbed on a filter adsorption net and prevent the dust from diffusing everywhere.