The invention relates to a construction method of a prestressed carbon fiber plate for reinforcing a beam by distributed anchoring. The construction method comprises the following steps that 1, pasting colloid is coated on a surface to be reinforced of a beam to be reinforced; 2, the two ends of a carbon fiber plate are connected with a tensioning part correspondingly, a first end face of the carbon fiber plate is attached to the surface to be reinforced of the beam to be reinforced, the tensioning part is fixedly connected with the beam to be reinforced, and the carbon fiber plate is tensioned by the tensioning part before the pasting colloid is solidified until the carbon fiber plate generates the set prestress; 3, the pasting colloid is coated on a second end surface on the opposite side of the first end surface of the carbon fiber plate and the surfaces of a plurality of pressing parts, the surfaces coated with the pasting colloid of the plurality of pressing parts is attached to the second end face of the carbon fiber plate, the surfaces coated with the pasting colloid of the plurality of pressing parts are connected with the beam to be reinforced through an adjusting part, the adjusting part is adjusted, and the carbon fiber plate and the beam to be reinforced are pressed through the pressing parts; and 4, after the pasting colloid is solidified, the end part of the carbon fiber plate is cut, and the tensioning part is taken down. The construction method has the advantages that the reinforcing effect is good, and the carbon fiber plate does not fall off.