The invention relates to a fixed bed reactor used for low-temperature continuous pyrolysis treatment of waste circuit boards, and a method thereof. The reactor comprises a feeding opening, a reaction chamber, a discharging opening, an electrostatic separator, a solid carbon collecting bin and a metal collecting bin, the feeding opening is arranged above the discharging opening, the reaction chamber comprises a feeding screw, a discharging screw and a material plate, the material plate comprises a feeding end and a discharging end, the feeding screw is positioned under the feeding opening and at the upper portion of the feeding end, the discharging screw is positioned at the upper portion of the discharging end, the discharging end is arranged above the discharging opening, the feeding screw comprises a center screw rod, a left screw blade and a right screw blade, the center screw transversely traverses through the left screw blade and the right screw blade, the left screw blade and the right screw blade are vertical to the center line of the center screw and are axially symmetric, a distance between the left screw blade and the right screw blade is 1/3-1/2 of the caliber of the feeding opening; and the solid residue inlet of the electrostatic separator is connected with the discharging opening, the solid carbon outlet of the electrostatic separator is connected with the solid carbon collecting bin, and the metal outlet of the electrostatic separator is connected with the metal collecting bin. The reactor and the method have the advantages of realization of continuous treatment of the waste circuit boards, simplicity in operation, and high economic benefits.